Quote Originally Posted by wumply
When I put my XP CD into my CDROM I get 4 options:

Install XP
Install optional components
Perform additional tasks
Check system compatibility
To run a repair you have to "Boot" from the XP CD and not run the CD via Windows,which is what you are currently doing.

As lynchknot explained,you first have to set the CDROM as First Boot Device.
Restart your machine and hold down the Del key until you enter the BIOS Setup screen.Select Advanced BIOS Features and use the arrow keys to highlight First Boot Device.

Use the Page Up/Page Down keys to change the device to CDROM.Press Escape and then select the "Save and Exit" option.Type Y to save.

Your machine will now reboot so put your XP CD in the drive.And during the Power-On Self Test (POST) when you see the Boot from CD message at the bottom press any key.

Then follow the instructions in the link posted by Coffee.