Oh if you mean the linux liveCD, I usually use Knoppix (
www.knoppix.com). I believe it is comes in a ZIPPED ISO file. So may be you need to extract the ISO file into your Desktop. You will need Nero or ImgBurn (I use ImgBurn) to burn the ISO image into a blank CD. If you are using ImgBurn, pop a blank CD in your drive and just right-click on the ISO file, then choose
Burn with ImgBurn.
Leave this CD in your laptop drive and reboot. Make sure you can boot from your CD/DVD drive. Sometimes you must need to change the boot order in your BIOS settings to be able to do this.
EDIT:
It will not work in XP as it is not an application. It is a totally different operating system that you run from your CD drive. The good thing is you do not need to install this in your hard drive - meaning no formatting, no partitioning involved.
EDIT 2:
Btw, did the laptop come with XP or was it Vista initially and only downgraded to XP recently?