Back in the dim and distant past, I blogged about desktop search in general and Google Desktop Search specifically. In that post, I lamented the search tools of yore that went away for one reason or another. A commenter kindly pointed out that my all time favorite (Magellan) now lives on as X1..
Lo and behold, Yahoo has entered the fray with their own desktop search tool, based on X1. In fact, it is a free version of X1 that doesn't include the enterprise features. It has a slick Windows-based UI and does a lot of cool tricks. So, I displaced Google and installed Yahoo Desktop Search (PCMagazine also gave it their editor's choice).
Well, after using it for a while, I'm un-installing it and going back to Google. Both are in beta, but Google is much more stable IMO. Yahoo was constantly doing odd things, and seemed to be belly up when I needed it the most. While Google has a sparser UI and doesn't handle as many file types, it is (at least for now, for me) more stable. And, for infrastructure software like desktop search, stable wins the day for me. I'm writing this while un-installing Yahoo and re-installing Google. Maybe once Yahoo turns 1.0, I'll re-evaluate. But for now, I'm switching back to Google.