If you Google the word "Google," you get Google (NASDAQ:GOOG). If you Google the term "Google Duel" in a few weeks, you may very well find yourself here.

True, that's unlikely to happen. GoogleDuel.com is an established site that lets users pit word against word for search-engine popularity. That still shouldn't stop us from striving to reach the top spot. At least this feature is practically anchored to the top of the results when you Google the term "Dueling Fools" on the world's leading search engine.

Well, maybe it's not the world's leading search engine -- just one of 'em. Baidu.com (NASDAQ:BIDU) is trouncing Google in China. Yahoo! (NASDAQ:YHOO) is huge in Japan. Microsoft (NASDAQ:MSFT) is too cash-rich to not put up a fight, either.

Search engines are the key to online advertising, because they attract information-seekers. You and I hit up a search engine because we want to be somewhere else, and advertisers love that. Google has surfed that wave perfectly, but now, as it teeters up and down from the $500 mark, have the shares become overvalued?

Not all Fools agree. This week, Anders Bylund feels that things are just starting to heat up, while Chuck Saletta thinks the stock's valuation has gotten out of hand. Where do you stand? That's what this week's bout is all about.

Duel on!

Longtime Fool contributor Rick Munarriz holds no financial position in any companies mentioned in this article. Yahoo! is a Stock Advisor pick, Microsoft is an Inside Value selection, and Baidu is a Rule Breakers pick. The Fool has a disclosure policy.