Well, since my purchase of an AGP Radeon 4670 didn't work out due to my 3.0 GHz Pentium 4 not being able to keep up, I've decided to completely rebuild my desktop with new(er) components.
These are the specs:
Core 2 Duo E8400
Asus P5Q3
4 GB DDR3 PC3-10666 (1333 MT/s) Memory
Radeon HD 4670 for PCI-E 2.0
ATX12V v2.3 Power Supply
The (cheap) video card is more than enough to play DoD:S and L4D2 at 1440 x 900. The main thing is, this will get me off of AGP, off of my laptop, and onto a desktop with PCI Express 2.0.