I bought a Compaq Presario notebook that came with many games that I don’t use. Can I increase the available memory by deleting all of the games?

You can increase the disk storage space that’s available to you by deleting the games, which take up room on your hard disk. But that isn’t the same as increasing “available memory.” Memory is the capacity of the computer to manage data at any one moment, and it is governed by the random-access memory, or RAM, inside the machine. Unless any of the games, or some game-launching programs, are automatically loading into memory when your PC starts up, the games aren’t wasting memory, just disk space. Getting rid of the games is still a good idea, but don’t try to do so by simply deleting them, as you would a file. You should do it by properly uninstalling them using the Windows uninstaller control panel, which is called “Add or Remove Programs” in Windows XP, and “Programs and Features” in Windows Vista.

I plan to buy an Intel-based Mac. I will need to run some Windows software for school. If I use Parallels to run Windows and the Mac operating system simultaneously, and someone does happen to get me with a Windows virus, can that migrate over to the Macintosh side of my computer?

First of all, I can’t stress enough that anyone running Windows, on any hardware — even an Apple computer — should obtain, install and run Windows security software, including antivirus and antispyware software. I do so, not only on my physical Windows computers, but on the virtual Windows computers that run on my Macs via Parallels. Even if you are using Apple’s own Boot Camp solution for running Windows on a Mac, which doesn’t allow the two operating systems to run simultaneously, you should be running security software on the Windows side. Such security software is primarily intended to protect the Windows environment on a Mac. It is unlikely that a Windows virus could migrate onto the part of the computer controlled by the Mac operating system, and even if it did, it couldn’t run there if it was written strictly for use in Windows. It could run only in the faux Windows computer created by Parallels. However, the people who write malicious software are relentless and creative, and it’s impossible to rule out anything they might try, or do. There is one danger to your Mac in this scenario. Parallels includes an optional feature that allows Windows, and Windows programs, to access folders and files on the Mac side of the machine. If you turn on this file-sharing feature, and if you get a virus whose purpose is to delete or corrupt files, it could attack these Mac files, because Windows has access to them. So, for maximum security, I’d advise that you leave this feature off. But, even if you do so, you should still obtain, install and use Windows security software for use when running Windows.

In your column last week about the Ooma device that gives you free domestic phone calls over the Internet, you mentioned that, until the product goes on sale in September, the company is giving away 1,500 free models, but only to people who have been given a special token by existing owners. Can I get one of your tokens?

Sorry, even if I had been sent enough tokens to fulfill the numerous requests I got, I couldn’t fulfill them. I am sending my few tokens back to the company, along with the Ooma gear I was lent for my testing. For ethical reasons, I don’t keep the products companies lend me for review, or take anything of value from them, including tokens entitling people to get a $399 product free of charge. Nor can I help the numerous other readers who asked me to get them on Ooma’s free distribution list.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Write to Walter S. Mossberg at mossberg@wsj.com

But relatively few Americans have adopted these alternatives, which are called voice over Internet protocol services, or VOIP, for short. Some consumers avoid the move because VOIP services can’t connect to 911 emergency call centers in the traditional manner, and must use workarounds. Others worry that if their Internet service goes out, so does their phone service.

In addition, the stability of the VOIP providers isn’t certain. Vonage itself has been battered by legal problems and another VOIP service, SunRocket, shut down this week.

I’ve been testing a new type of VOIP option that will go on sale in September from a Silicon Valley start-up called Ooma, whose product goes by the same name. It differs radically from Vonage and other current VOIP providers, in two ways.

First, Ooma is a $399 piece of hardware that you pay for only once. There are no monthly bills. You just buy an Ooma Hub, a small device that looks like an answering machine. You plug it into your Internet connection and attach a phone, and you get free, unlimited domestic calls, local or long distance, as long as you keep your Ooma.

Second, with Ooma, you can easily keep your regular phone service as an integrated backup, for 911 calls, and in case the Internet service in your home goes out.

Ooma combines the VOIP and regular phone service. If you keep your standard phone service, Ooma uses your current phone number. And, if you dial 911, it always places that call over the traditional phone network. During an Internet outage, the device seamlessly switches to use the regular phone service, but you still pay no fees to Ooma.

If you do keep your standard service, you can reduce it to a very basic, low-cost plan, just for 911 and backup. International calls are routed through the Internet by Ooma and the company says they will cost roughly what Internet phone services like Skype charge for nonmember calls, which is well below traditional landline rates.

Ooma also delivers some added benefits. It gives you a virtual second line. If a call comes in when you are already on the line, the second call can be answered from another extension. It also has a built-in answering machine, and allows you to check your messages and call logs online.

I’ve been testing Ooma in my home for about a week and, except for a problem on one phone jack, I found it worked as promised. I tested it with both corded and cordless phones, and I also tested a companion $39 device, called an Ooma Scout, which must be plugged into the phone jacks in your house you want to use, beyond the jack to which the Hub is connected. Each scenario worked well.

When I plugged my cordless-phone base station into an Ooma box, all of the remote handsets continued to work normally. The only difference was the dial tone; Ooma gives you a unique musical dial tone to tell you it’s on duty.

Ooma works using the peer-to-peer Internet system popularized by file-sharing sites. Each Ooma box is part of Ooma’s network. The box in your home, for instance, might carry someone else’s phone call, though you can’t hear that call, and this doesn’t interfere with your own ability to make and receive calls whenever you want. In my tests, the Ooma didn’t seem to affect the speed of the Internet connection used by our computers.

To build its network, Ooma will be seeding the country with 1,500 boxes over the summer. These will be provided free of charge. But the only way to get one, if you aren’t on the initial list, is to know somebody who has one. Each recipient gets three tokens — redeemable for a free Ooma — to give to others.

Set-up is relatively straightforward and the manual is clear, assuming you have standard cable modem or DSL Internet service.

I did run into one problem. When I plugged my cordless-phone base station into an Ooma Scout, outgoing calls worked OK, but incoming calls wouldn’t work properly. This problem cleared up when I moved the base station to a different phone jack, but it suggests that, at least on some jacks, Ooma may fail.

The Ooma devices can be constantly updated over the network to fix problems and add capabilities, and the company is planning to add more features and options, some of which may cost money.

Of course, there is no guarantee that Ooma can handle a large number of customers as well as it did my test unit. But Ooma may be a good option for people who want to cut their phone bills, and either aren’t worried about 911 and Internet outages, or are willing to keep a basic, low-price standard phone service to cover those contingencies.

• Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.