Money aside, The PS3 probably has a slightly larger Call of Duty fanbase. An X-Box 360 probably has the highest number of CoD, or Battlefield:BC2 players. Also, you can by PS3 games used.
As for the PC, there is a better selection of shooters, and the gamers are usually more mature.
Another thing to consider, is we don't know how much life the PS3 has left, or any console from this generation. You may well only get two years out of it, before it is time to buy another system.
Woah thanks everyone for the replies.
I am upgrading my Graphics Card, Motherboard, RAM, and Processor. Here's what I'd get:
I am also considering getting a new tower, as the one I have (Antec Sonata II) has a broken front cover that came off when I pulled back a bit to far :p
Here are my current computer specs:
Windows XP Service Pack 3
Motherboard: Asus A8N-SLI Premium
Processor: AMD Athlon 64
Graphics Card: NVIDIA GeForce 7600 GS (512 MB)
RAM: 4 GB DDR2 (1 GB each RAM stick)
Power Supply is 400W
1 TB hard drive
Sound Card: Creative Sound Blaster Audigy 
I'd go for something like this:
That would come to about $465. Or you could keep the 5770 for $430.
What brand/model is that 400W PSU? I would be hesitant to run that kind of hardware on a 400W. It might be capable, but it would be pushing it. I would recommend something like this:
With the PSU your total would be around $500 with the 5770 or $$535 with the 5830.
Which ever you decide on, you definitely need a new PSU. I ssecond the Seasonic.
Power usage estimates for newer PCs are usually between 380, and 450 watts continuous. Most PSUs are Rated at max output, not continuous/sustained output. Furthermore, PSUs loose their ability to put out power as they age.
So your 400w PSU may only be as good as a 300w PSU, maybe 350w.
Either upgrade would be good. I couldn't stand my old setup, even a dual with a 7600 is only capable of 640x480 in most modern games. That 5770 will be a world of difference, and probably will not even break a sweat on your (assuming) low res (1280x1024?/1440x900?) screen. You might even be able to get away with a Radeon HD 5650.
The 5830 isn't worth the money, get at least a 5850. Or maybe, if money isn't a problem, get a 480? :D
Woops I thought the PSU was a 400W... Its actually a 500. Its an ATX Ultra V series. Should I get a new one anyway?
Also concerning the processors, is it worth upgrading from a 3 core processor to a 4 core? I know that most games now a days don't take advantage of all 4 processors. I've also noticed that the X3 I picked has a .2GHz lead on the X4. Does that .2GHz make a huge difference in terms of gaming performance?
That ultra is just terrible.
ZeroPressence;5402266 Also concerning the processors, is it worth upgrading from a 3 core processor to a 4 core? I know that most games now a days don't take advantage of all 4 processors. I've also noticed that the X3 I picked has a .2GHz lead on the X4. Does that .2GHz make a huge difference in terms of gaming performance?
Yes, at this point i think a quad core is definitly worth it, even if its a slightly slower clocked model. Besides, if your really worried about that 200Mhz you could overclock that X4 to the same speed in about a minute.
I don't know if those AMDs support a dynamic clock feature or not. I remember reading that AMD was working on one.
Intel's Core i processors will dynamically increase their clocks if not all the cores are in use. If that AMD does so, then it will probably run 200mhz faster when only using three cores.
I'm not much of an overclocker anyway :) And I'm still not sure weather to buy the quad or triple. Is their gonna be a difference in speed from a triple to a quad?
Do I still need a 620W PSU? I have a 500 right now.