You will of course need the DVD or USB drive setup with Windows 7 install package. At that point setup your BIOS to boot to DVD or USB depends on the media setup.
The Windows 7 install process will then begin. All applications and documents stored in other locations will have to be reinstalled / transferred manually.
For more information on the Windows 7 Upgrade, please go here: http://bit.ly/3DvynK
For additional assistance with the migration of Windows XP to Windows 7, please go here: http://tinyurl.com/mhbep4
Microsoft Windows Client Team