Sounds like you want something a little worse than my PC, and it stresses me out a lot and makes me wish I had a never PC, however compared to my old one, its nice and powerful, except the OS is buggier.
If I knew you personally I would give you mine as soon as I got a new one, as I did to a friend with DBC, dark matter and TrueSpace.
What I would suggest is look at your budget and see whats the best custom PC you could build, custom builds are usually cheaper than new PC's as for second hand comps, not a clue, ebay is the place you will most likely find something, however you run the risk of a scam, just just their comments, number of positive comments (if theres a high number you can trust them the most you can for a geezer on the net) and look at the page, if anything looks dodgey, keep away
Yey! I removed the sig...
A Llama called Dalai