windows xp?

You can't uninstall Vista and roll back to XP.

You need to backup your personal data, format the drive and do a fresh install of XP. During the installation process, you have the option of reformating the drive or chose another drive/partition if you have more than one.
There is absolutely NO obligation to install on the C: drive, here, windows is installed on the E: drive of my computer.
You can then restore your data.

It greatly help if you have more than one drive, or two partitions where your data are not on the same drive/partition as Windows.

Electro
June 2011