CPU should be able to run AH okay, as long as you trim back a lot of the stuff that Vista runs by default. It will suck the performance out of your system if you let it.
Your main problem is your video card. That's the kind of card that can barely run spreadsheets, let alone games. It's integrated onto the motherboard and will only cause headaches if you try gaming with it.
The easiest, most cost-effective way to get back into the game is to research what kind of add-in video card you can currently support, get one, and disable the onboard video.
Chances are that you won't be able to do that with a 250W power supply, though, so you'll need a new PSU along with the new video card.