Looking to buy another PC, suggestions?

I have three already. A cheap one I bought at Wal-mart, one I got from a campus instructor, and my Dell. The first two; an XP and something idk what cannot run games without lag. The Dell is duel core Vista 64-bit works fine with most games. But I had to replace it's memory twice and pay to get it out of a loop once (same price). Because of that I'm mad at Dell.

I am not a Computer Geek. I can put in a graphic's card and clean out the dust specks. That's it! I am NOT learning how to put a PC together from scratch. I am also not running a heavy duty extension cord from my laundry room to power a high tech gaming PC.

No.
No.
No.

That said, what over-the-counter PC do you recommend (if you say Mac I'm barfing) I purchase?