Demomen are definitely the most versatile class.  You could almost have a team consisting of nothing but Engineers and Demomen on defense, and Medics and Demomen on offense, because they can fill so many roles if they coordinate effectively.  My max kills/points as a Demoman is 16/22.  "Only" 3617 damage.  ;)

I'm not a very good Spy either, but in one Dustbowl game on defense, I managed to knife 9 people in the span of about 45 seconds.  That's one person every 5 seconds, and the opposing team only had 11 players.  :D  I can't seem to be that good consistently, though, I always get too excited/flustered and give myself away.

I'm absolutely horrible with technical stuff, but I think the problem with my computer is exactly that the graphics bits are integrated. Lots of games, even ones older than the computer itself, simply refuse to run because there's something critical that isn't compatible. My roommate puts computers together pretty much as a hobby, and he once took a look at it and told me there's nothing that can be done for some reason I can't remember. 

I'm sufficiently encouraged by this thread to at least give it a try though. Won't get much work done for a few weeks if it works. =P

It's possible you don't have an AGP or PCI-Express port...which would greatly slim your options of putting a new graphics card in your computer.

Still, you should look into it on newegg.com. There's decent graphics cards from a couple years ago that are under $100 that would improve your gaming many times over.

TF2 owners add my steam id: matts733