There has been a lot of buzz of Windows 7 ever since its Beta has come out and several customization packs have also cropped up to convert XP/Vista to Windows 7 but none is as good as Seven Remix XP. It is one of the best Transformation Pack I have seen that can be used to convert your XP desktop to Windows 7 Desktop. It is also being constantly updating the transformation pack as well and the developers just released the second version of the Seven Remix XP very recently as well.

The transformation pack includes:
-> Shell32.dll, explorer.exe, imageres.dll icons
-> imageres.dll images (Logon screen)
-> Aero7 v0.1 Visual style

This Pack works on the following operating systems and languages:
-> Windows XP (Home, Pro, RTM, SP1, SP2, SP3, Corporate)
-> Windows 2003 (Standard, Enterprise, Datacenter, Web, RTM, SP1)
-> Windows Media Center Edition (2003, 2004, 2005)
-> Windows XP Tablet PC Edition

Note: It does NOT work with 64 bit versions of Windows

Download Seven Remix XP

Update:  This Pack is constantly being updated by the developer. You can check the latest version of Seven Remix XP here.