Microsoft wants you to start using Windows Live Search to shop instead of rivals Google and Yahoo, and in return is willing to pay you cash.

The new program, called Live Search cashback and rolled out at the Advance 08 advertising conference in San Francisco Wednesday morning, promises to pay back users who find and buy products using its search engine between 2% and 30% of the purchase price.

Live Search cashback is actually a rebranded version of Jellyfish Cash Back, which Microsoft acquired last October. Jellyfish's core product is a comparison shopping engine, and Microsoft needed something to compete with Google Shopping, formerly called Froogle.

Jellyfish will remain a separate site, focusing on its other offerings like its "Smack" shopping that features products with constantly falling prices. Shoppers can wait for a lower price, but they may miss out as Jellyfish does not list how many units are available at any given time. The company also has a social network for shoppers.

According to Microsoft, millions of products from hundreds of brand names are available from Live Search cashback. Savings on a purchase will be deposited to a PayPal account, bank account or sent via check in the mail. It will only be available after 60 days, however, and can only be withdrawn once the user has accumulated $5.

Beyond enticing users to make more searches with cash rewards, registering a Windows Live account with Microsoft is required to track purchases, further bolstering the company's user base.

In a FAQ about the service, Microsoft says it is offering Live Search cashback because, "We want to earn your loyalty and reward it with cashback savings for your everyday online shopping. We are 'The Search That Pays You Back!'"

This isn't the first time Microsoft has resorted to financial incentives to lure new users into Windows Live Search. The company saw moderate success in increasing its market share last year thanks to Chicktionary, a game that rewards users with prizes such as software. Players rearrange letters into words, and a Web search is automatically launched for each one.

But the boost to 13.5% of the market was temporary, and Windows Live Search has since dropped to single digits, according to comScore and Nielsen NetRatings. Microsoft has since launched three new games to its Live Search Club page, but none have caught on like Chicktionary.