... Should we buy a new motherboard, CPU and video card, or can we get by with just a CPU upgrade on his existing motherboard and the purchase of a new video card ...
Why not buy a used system for about $400? I don't really know how much used computers go for in the US, but they can't be THAT much more than here in Sweden.
That way you upgrade everything to a decent standard.
I looked at one of the sites selling used computers over here, and this is what you get for $364 (the first hit):
CPU: i5 2500K@3.3GHz Boxed Unlocked
Motherboard: Gigabyte Z68AP-UD
RAM: 16GB, 1333MHz
GPU: AMD HD5550, 1GB DDR-II
SSD: 1x80GB, 3GB/s
HDD: 2x1TB WD Green
CHASSI: CoolMaster Tower
OS: Windows 7 Home Premium 64-bit
OTHER: DVD, MS-3000 v.2 wireless mouse/keyboard, MS-5000 wireless mouse
I'm sure you can find something better on your own.
