Ok, I feel the need to clear a couple of things up: When a graphics card advertisement says that it requires a minimum of #Watts, it is referring to the entire system. It will not use 300W when it says that it has a 300W power requirement. I'll just reference you to an example on NVidia's web site...
http://www.nvidia.com/object/geforce_gtx_280.html ... click on "specifications", and scroll to the bottom. You will see "Maximum graphics card power" and "Minimum System Power requirement".. note how the minimum system power requirement is the advertised level, and yet it's obviously not what the card actually uses. The designers know precisely how much power is required for a graphics card to operate, but they are just assuming power usage amounts of other components in the system, to make it more convenient for the consumer.
So, Purple Poison, I assume by your statement that you don't care what the graphics look like that the rest of your computer isn't extremely high-end, and if that assumption is correct, then you should be perfectly fine with any card these people throw at you. I have a friend with a 400W power supply running two 8600GTs, both of which claim a 350W minimum power requirement. (if I'm remembering correctly from when I recommended them. I can't find anywhere to confirm it, though.)
Also... someone recommended the 9600 GT... it says that it requires PCI-E 2.0 16x. This may or may not work with a PCI-E 16x slot. It did with my computer, (SLI didnt' work, but a single card did) but there is always the possibility that the thing will die on you. I just don't know what would happen.
Now for me to recommend a card will probably not be the best, because I am completely obsessed with having perfect performance. (Aspiring overclocker) I will probably not be the best judge of cards for you, since I would prefer to spend an extra $30-40 to double performance, but you wouldn't. The best thing I see is
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150247. It has 512MB ram, is fairly fast (it's close to what I used to have, except mine was EVGA. Everything else looks identical, except it's DDR2, not DDR3.) It served me well... Two of them survived Crysis (25-ish fps) with mostly medium settings (textures & shader quality high, all else medium except for postprocessing, which was low) at 1024x768... I'm certain that one of them would run COD4 with at least minimum settings.
Now... although the above will float your boat, my personal recommendation is this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127325. I'm currently using two of them, and they dominate Crysis on all high settings, (not very high. I use DX9.) except for occasional glitches. One of them will work in a standard PCI-E x16 slot, instead of PCI-E 2.0 16x. SLI will never work, but that's definitely way outta your ball park. But then again... I did have many driver issues, some of which still havn't been fixed. However, the only place I've ever seen these glitches is in Crysis, which you don't care about... so it should do COD4 with zero errors, with at least medium settings with a good resolution. It has the best performance/price ratio of anything currently available in my opinion.
Pain &
P.S. - w00t for pyromania!
