Just to illustrate how much I've been paying attention to hardware advancements, my first reaction upon starting to look a couple of days ago was "Holy shit, they have six-core processors now?"

I need a computer capable of running at least semi-modern gaming graphics, as well as the capacity to handle video editing in After Effects (something my current PC can do, but tends to take a long time grinding its way through). I don't play first person shooters, which is where the really graphics-intensive games tend to be; the highest detail thing I'm even considering getting is Dawn of War 2. So really my requirements aren't (I think) very stringent and I'm looking for a deal; being under-budget would be great. However, the other consideration is that this will be the third time I've bought a computer, and the last time was four and a half years ago, so I also need one that will last me awhile, since I tend to hold onto my hardware until it genuinely can't hack it anymore or it starts falling down around my ears, so I don't want to buy something barely adequate only to find out it can't handle software advancements in the foreseeable future and/or that it's a piece of crap that'll wear out two days after the warranty expires. Suggestions?