I use a dual processor AMD Opteron system that is far too old, but I'm far too cheap to replace it. It cost me about 2k and is as solid as a rock. I try not to fool with rock solid. I purchased from a boutique provider that knew their shit ... not a bulk manufacturer more interested in profit.
I've got less RAM and less processing power than most, but this brings up a point.
Everything in the recording chain moves in this fashion in order of import:
Source->Mic->Preamp->Recording Device->Sound Card->Computer ...
... unless dirt crap exists in the weakest link of the chain ... and the sound will occur accordingly.
If you've dirt crap for source (the actual performance), nothing you do following will matter. If you've dirt crap for mic, recording becomes dirt crap ... and nothing that follows will matter. Noisy pre? Bad sound ... and so on and so on down the chain.
This is important advice. Learn to discern. Use your ears to know the diff.
Best,
Kev-