I have used Windows XP more than any other OS from Microsoft and in fact I still have a test machine that runs Windows XP.
Back in the days Windows XP was a huge overhaul from Windows 98 and the failed Windows Millennium, however that look has stuck with me for quite sometime.
Also Read: Stunning Windows 7 Wallpapers
If you are using Windows 7 and are nostalgic like me about Windows XP, you can now download a Windows XP theme and use it on Windows 7.
XP Luna is a theme for Windows 7 that will bring the look and feel of Windows XP to Windows 7, definitely worth it if you want the simple looks of XP and the power of Windows 7.