To date, the company–which makes the leading open-source ad serving software, catering to about 30,000 Web publishers on 100,000 Web sites–has raised $30.8 million. “We raised $15.5 million at the end of 2007 and still had a chunk of that left, so we didn’t have to raise money,” OpenX CEO (and former Yahoo Senior VP) Tim Cadogan told The Deal. “But if it’s generally true that it makes sense to raise money when you don’t need it, in this environment, it is triply true.”

Quadruply true when you’re competing with the likes of Google’s (GOOG) Double Click and Yahoo’s (YHOO) Right Media, which dominate the Internet advertising market in which OpenX plays.

Former Yahoo Senior Vice President Tim Cadogan will take the CEO job at OpenX, the popular open-source ad server start-up, backed by Index Ventures, Accel Partners and others.

As part of the change, the company will move from its London HQ to Los Angeles. OpenX has about 30 employees, including 10 developers in Poland, but not all will be moving West.

Cadogan was with Yahoo (YHOO) for five years, in its search unit and later as SVP for ad products, including playing an important role in the launch of its Panama ad search product. Previously, he was an early member of the GoTo.com team and went to Yahoo just before it acquired Overture.

Cadogan will now run OpenX (which recently changed its name from OpenAds), which makes the leading open-source ad serving software, catering to about 30,000 Web publishers on 100,000 Web sites in more than 100 countries.

Until now, OpenX has been helmed by James Bilefield, another former Yahoo exec, who was also VP of Global Business Development and GM of European operations for Skype.

OpenX has raised about $21 million in funding since 2007. Besides Index and Accel, other investors include First Round Capital, Mangrove Capital and O’Reilly AlphaTech Ventures. Former AOL head Jon Miller also recently joined its board as chairman.

“With open-source software, there is a lot of potential for business disruption and to open up the market,” said Cadogan in an interview with BoomTown from London. “You have not really seen open-source models really applied to the ad space until now…but there is a big business in giving publishers a really robust offering and a platform where they can also share what they build.”