A Geforce or Radeon graphics card will do fine unless you want to get into 3D apps like Maya. Obviously, you want a graphics card with plenty of memory on it for high-res work. Max out your system RAM, and get yourself a large hard drive.
The tricky part is the monitor. Gaming LCDs don't have a ghosting problem, but their color reproduction isn't on par with professional graphics LCDs. Those LCDs though, have much longer response times, so they have a ghosting problem. Ghosting does not affect photo editing or any of that, it will only mess up games and movies. If you want it all, you may need to clear your desk for a good 21-22" CRT. Those babies don't have the ghosting problem and they have historically had the best color reproduction.
I almost forgot, get yourself a good Wacom Intuos3 tablet. Those are totally awesome for 2D work.