bit-tech published a review of Microsoft's Sidewinder Mouse

Technically the Sidewinder is a good mouse and on paper it has all the features one might look for -- on the fly DPI, thumb buttons and an ergonomic design which isn't entirely uncomfortable to use. On top of this it adds a load of features which range from pseudo-useful to the downright annoying, such as the weight system and Game Explorer button.

The mouse even performs quite well and I tested it across a number of games in the week I had it on my desk, including the awesome / /Team Fortress 2.

However, the mouse isn't exactly the most comfortable to use and the Intellipoint software hinges on being needlessly elaborate. Some of the
features, the Game Explorer button in particular, are entirely stupid and do absolutely nothing for us. The overall look of the mouse is also a bit repugnant, which makes the price even more annoying. The Sidewinder costs around £40 in the UK or $65 in the US.

At that price, the Sidewinder is starting to put itself out of the market and for just a little bit more you can get a much better mouse, like the Logitech G5, or you could get a Razer Deathadder for the same price.

Microsoft Sidewinder gaming mouse Review