Use Windows 7 Theme

You can use windows 7 theme without any problem. It is totally free. At first download here,

After download unzip this file. And then install this file 'Uxtheme Multi-patcher 6'. Then your windows see windows fatal error. Then cancel it and restart your PC. Then copy 'seven' file from unzip file. Open 'C:\windows -->resources-->'themes' And paste it in this folder. If you want to see your 'Windows 7' theme then go seven folder here you can see a file by name Seven. Double click there.

Source: http://zmdark.deviantart.com/art/Windows7-PDC-2008-theme-for-XP-102729431