Remove Vista from Dell and replace w XP

Ok, I'm computer illiterate and broke, so I am placing myself at the mercy of the computer Gods.

Last year I replaced my fried 8 year old Dell PC with a new one. My old one had Windows XP and I loved it. THIS one came with Vista 64 bit home premium. It took some getting use to, but it is sooo slow. Besides that I have random problems with stuff I never had before, sites that I cant visit, and things that wont load. I got to the point where I dont even use my PC for anything but balancing my checkbook and Facebook because it is sooo frustrating.

What I THINK I want to do is completely wipe my machine and install the operating system and drives from my old one. This is probably not a good idea, but I figured it was worth a shot to get some feedback on. I would be doing this with the re-installation CDs that came with my Dell back in 2003.

I have an HP laptop with windows 7, but it was a refurb and so I dont have the reinstallation cd for it or I would go with 7 instead of XP.

Another thing ... My ex boyfriend used my PC more than I did for about 5 months and he loaded all kinds of stuff. He only exacerbated the problems I had from the start. I cant use my media player at all ... I use to though.

If nothing else, I would want to return the PC to the original NEW state untill I can afford windows 7. At the least I can start again with everything working and try to keep it as clean and smooth as possible.

Any thoughts?

Barbara