The goal is to build a CPU that will be able to run games better then my Xbox 360 and be able to perform tasks on the computer at a much more efficient rate. A lot of games extremely terrible on consoles. (Fallout: New Vegas's load times are horrid, for example). I'm not worried about graphics, performance mainly. I understand I won't be able to run modern games at the highest settings.
System Usage from Most to Least Important: Gaming, Multitasking, Web Browsing (Mainly upcoming releases: Battlefield 3, Mass Effect 3 etc.)
Parts Not Required: Kyeboard, Mouse, OS*, Monitor* and Speakers
*= I currently have Vista (unless Windows 7 is a huge upgrade from Vista I'd rather save up $100 and buy it later) and my current monitor resolution is 1600x900. I'm not sure what current monitor resolutions are, so I may need to get a new monitor as well.
Preferred Website(s) for Parts: Amazon, Newegg
Country of Origin: USA
Parts Preferences: by brand or type: I would prefer a quad-core processor, an Intel i5-2400 is my first thought. I know it''s a bit expensive so an AMD Phenom II x4 will do fine if required. Although the i3-2100 is better for gaming, I'd prefer a quad-core. I don't know about GPU's that support 1600x900 either.
Overclocking: Budget is too low to be considered.
SLI or Crossfire: Budget is too low to be considered.
Monitor Resolution: Current monitor is 1600x900 (it's somewhat old)
Additional Comments: Regarding the i3, are the two-cores really worth it? I do plan to have additional programs run while gaming, which is the main reason for a quad-core. I don't have much of a build yet so far (clueless if any GPU's can work on 1600x900) and haven't decided out of either 3 of the processors I listed above. I may end up upgrading the CPU/GPU overtime as well.
First, I think you need to understand that some games were designed for the XBox 360 and ported over to the PC. Some games were designed for the PC and ported over to consoles. Generally speaking, these ports leave a lot to be desired so asking for a system that performs better than a console is pretty much hit and miss. Since I don't game on a console, I can't make any recommendations as to components.
Most gamers tend to ask for the prettiest picture they can get from their monitor. That means the highest resolution they can afford. For most of us, that's 1920x1080 or 1920x1200. Some few have monitors with resolutions of 2560x1600. Others have three monitors in Eyefinity with a resolution of 5760x1200 (3 x 1920x1200). Obviously, the higher the resolution, the more powerful the graphics card(s) need to be. Since you're on a thin budget, I don't see any need for you to upgrade your monitor at this time (and thus trimming from an already slim budget).
Overclocking: You can get a small to modest overclock with the stock coolers (no extra cash spent) on some CPUs, so I wouldn't discount it out of hand. With the lower resolution monitor that you have, you won't need a top of the line graphics card. This may allow a bit of extra cash for a third party CPU heatsink/cooler (HSF), which would give you a greater over-clock capability (assuming the right motherboard/CPU combo). Again, I do not overclock my systems, so I won't try to make any recommendations there.
Windows Vista: I think I ran Vista on one system for about two days. I then upgraded to Windows 7 (only because it was available). The general consensus is that Windows 7 is far better than Vista, but again, we're dealing with a tight budget, so I'd probably hold off on the Windows 7 upgrade and put that $100 back into the system.
CPU: I've heard (not seen any benchmarks - I just haven't looked) that the Core I3 2100 will out-perform the Athlon X4 955 in (some?) games. To me, this is a no-brainer. More cores means more future-proof. I won't have to upgrade this system for a little while longer, so I'm with you in going AMD quad-core, but you need to look at whether or not an Intel based system fits within your budget as well as any overclocking potential.
GPU - Since you're running at 1600x900 (about half way between 1280x1024 and 1920x1080), you won't need a top-tier graphics card. However, since you're thinking about getting a higher resolution monitor in the future, it's not going to hurt to get a top-tier graphics card now. It won't be utilized to the fullest on your 1600x900 monitor, but you won't have to replace it when you upgrade the monitor to 1920x1200 either. Also, pretty much any GPU on the market today should be able to handle 1600x900 resolution monitors.
Now the parts aren't exactly the best in slot individually, and I know some people berrate Rosewill PSUs but... the price seems good.
For that resolution a GTX460 768MB or 6850 would be plenty as far as I know.
Not much difference between cards nowadays, so best to look for warranty/extras. Prices seem pretty close. I just noticed a $25 difference between the 6850s I was looking at and the GTX460s, in this case I believe the GTX460 1GB wins the deal.