I've yet to meet a Microsoft search tool that I like. Without exception, they're slow and ineffective, and I avoid them as much as I can. I use Copernic for desktop search instead of Vista's built-in facility, Google for searching the web, and GMail's web-based search when I need to find a message in my personal email accounts. The only time I rely on a Microsoft tool for is for searching my work email in Outlook 2007. Unfortunately that refuses to look in most of my mail folders due to some obscure indexing problem that, despite my best efforts, I have been unable to fix.
So the news that Microsoft is going to start effectively paying people who buy things they find through Microsoft's Live Search (but only in the US, natch) made me laugh. OK, so companies give cash incentives to use their products all the time, but when it's a Microsoft search product that's involved it's hard not to be scornful.
