Hmm, I have an HP computer that is now a couple years old. I think I got it in early 2006. It's possible I got it in 2005. It's a single core with 1 gig of ram. I have CS1 and this computer handles things just fine. Pretty much zero waiting when working with 8mp 16 bit TIFF files that are about 46 megs....while tacking on 6+ layers. I can see the file getting over 500 megs on the thing below in CS. Still, there is zero problem handing it. The computer fan rarely comes on. Oh yeah and I'll have audio streaming online in the background, several tabs open in Firefox, Neat Image open, RawShooters Essentials open....all at the same time as CS and whatever I'm working on.
I also have a copy of DxO optics I was given. If I run that thing by itself to convert a RAW file....LOL.....my fan doesn't stop running. That thing is the biggest hog ever, so I won't use it. But CS, seems to be far from a hog since this computer handles it and other stuff at once as smoothly as you get. Maybe CS2 or CS3 have become a hog? CS isn't. Of course I don't have the HOG that is Vista on here either.
As for CS and $600+. When I got mine a couple years ago I got it on Ebay for around $300 new. What the Ebay store was doing is selling you a PS 6 or 7 cd and an upgrade cd of CS. Much cheaper route.
I noticed while messing with Lightroom 2 trial my fan was running a bit more frequently, much more than CS, but nothing like DxO optics.