AABoeing wrote on Jul 27^th, 2011 at 11:41pm:

Would I be able to do this if I had Vista on my computer when I bought it? And, would restoring my pc to factory settings help? That is the very last resort.

It's difficult to say. If you bought an OEM computer (Acer, HP, Dell, IBM etc.) they come with an OEM Operating System that can only be activated on the computer you bought from them. To change it to Win XP, you would need to ask the manufacturer if they can change it to XP. I don't like your chances of that though. Microsoft no longer support Win XP (so they say).
If you bought the system from someone who builds and sells them, then the chances are that you still an OEM version of the Operating System on it. Some come with pirated version of an Operating System, but that isn't all that common, I hope (wishful thinking on my part?).

If you search places like eBay, you might be able to get your hands on a cheap legal version of Win XP.

If you got a disk with the computer you bought, which is highly unlikely these days, you can reinstall from it. Otherwise you might need to do a "Restore" (from a hidden partition on the HDD) which will most likely wipe everything on your computer and return it to the way it was when you got it. Back everything up before you try that! :-/

Mark

BTW. Data Execution prevention is usually turned on and off in the BIOS.