Nice system... but kind of a weak video card. You really don't need massive case cooling with the A64 - they run pretty cool, even when you overclock 'em. I've got a 2800+ at 2.2 GHz. and it runs mid 40's under load with just a couple of regular 80mm case fans.
Actually, it wont. The 5200s are loaded with all sorts of hardware that they are not strong enough to use. Check with the guys in the graphics forum. Dont tell them you are going to spend a small fortune on a chip and mobo, but want a cheap graphics card though. Just tell them you want to replace your old graphics card, and have $X. Also tell them that you dont game, and that your mobo supports 8* AGP.