A 6200 or a 6600 regardless of how much memory, regardless of what clock rates and with any processor in a motherboard that doesn't even have AGP will NEVER run COD 4.
You never mentioned your processor but I suspect that its junk considering the motherboard.
I'm sorry but there is no point in trying, I felt the same when I had a 64MB 7300 LE and I was trying to get the what ever I can out of it till at the end I realized that I need a new PC. I tried 6 series cards but they are way too outdated, I use them as paper weights, I have one on my desk right now.
Invest a good $500 in a budget gaming rig and you can play everything, see the recommendations on this website.
hello and yes i run call of duty 4 and 5 (the zombie maps work best) and even play online on HIGHEST (cpu based not GPU) settings thats 1280x800 res and all textures at EXTRA but anti-aliasing and other gpu needy things make the FPS go way down
i run it around 45-50 FPS on a P4 3.2Ghz and 4gb ram
this is also thru a dvi-hdmi cord to a 32" monitor
so yea the geforce 6200 is great but i wants to run black ops
(the 5770 when o/c is close to the o/c 4890 shown) The regor when o/c to 3.6ghz is a bit faster than the phenomIIx2 shown.
The bigger the card, the more cpu power you need. The i5-2500K when overclocked is currently the fastest cpu for gaming. 570's in sli or 6950's in crossfire are needed to match this fast quad core cpu.
A pair of 460's or 6870's do pretty good too when paired with the overclocked phenomIIx4 3.4ghz o/c 3.8ghz