Someone needs to remind Microsoft that we’re in a recession, AdGooroo unveiled their third quarterly report detailing several key performance indicators for Google, MSN and Yahoo!, such as changes in share of advertisers. Microsoft’s increase in active first page advertisers for Q3 was the biggest quarterly increase since AdGooroo began measuring advertising activity, and in just one year, Live Search has grown their active advertiser base by almost 32 percent.

“MSN looks to be in a strong position thanks to their ability to retain existing advertisers and bring in new ones in droves despite an uncertain economic environment,” said AdGooroo Founder and Chief Gooroo Rich Stokes. “We also measured a three percent increase in Google’s advertiser base; while Yahoo!’s active advertiser count dropped by 2.5 percent.”

While it appears that Google was taking steps to increase coverage (at least through July), ad coverage dropped to its lowest levels in August and September, suggesting that those two months may have been weak. Google also launched a new algorithm change in mid-September, which may be aimed at reducing low-priced inventory, a move which strongly favors big-budget advertisers.

Although MSN and Google generated significant growth in the third quarter, Yahoo! appears to be staying the course while it waits for the US government to approve its ad-sharing deal with Google. While Yahoo! showed a slight decrease in active first-page advertisers in Q3, there were no other significant changes in other metrics.