Hello and welcome.
What make and model is your computer?
This will help determin if your hardware drivers are available for XP.
Yes I think your games would play on XP,Vista is the issue not XP.
To install XP it is a matter of setting first boot device in BIOS to CD rom popping in the disk and following these instructions:
How to partition and format a hard disk by using Windows XP Setup program
To enter BIOS restart the computer and on the post screen it will say "Press ? to enter setup" ? could be F1,F2,Del or another key.Press the key it tells you to.Locate boot tab or boot order in the list and set CD rom to first boot device and hard drive to second.
Please note after popping in the XP CD:
You will be prompted to press any key to boot from CD/DVD then press any key,any other time you are prompted to press any key to boot from CD/DVD do NOT press any key as this starts the install process all over again.
If you need further help with this please ask.
Jelly Bean.