Download Windows 8 Theme For xp and 7 here.
Windows 8 will be launched in middle of 2012, till then if you want to make your computer look like windows 8 then you can try download and use it, I hope you will like this one as this looks nice as I have tried in my pc.
Donwload it and try it and enjoy it, Microsoft rocks and Windows 8 rocks as well.
Download it and enjoy this. I hope you will like this. Always keep your PC virus Free. Enjoy Windows 8 in your Windows xp.