Sabayon Linux + Beryl

Vista looks nice, Mac looks nice but Linux also becomes nicer when time progresses. For example the flavor: Sabayon Linux (Sabayon is actually an Italian desert). And it's free! The latest version comes with lots of extra's, even games. It also includes Beryl which means that if you have hardware acceleration on your videocard (most these days have) you can see some nifty effects like in the movie below. It's downloadable as a Live DVD which means you can boot your PC with the DVD in and then can see the full extend of what this Linux version can do without having to install it.

Personal view: Over the years I've seen many different versions to try and they get better every time but I'm not at the point i would switch completely.

If you want to read more see the website of these folks here.