Will keeping the same processor And Graphics Card but Changing the motherboard to a DDR3 Compatible board And Putting in 4Gig’s of DDR3 1333Mhz Ram. Do you think doing this will Increase my gaming performances in Games such as Battlefield Bad Company 2 or is the money better spent on a bigger graphics card
In most games you'll see improvements if you increase decrease your RAM latency rather than increase your frequency. The difference between DDR2 and DDR3 is bandwidth, not necessarily speed. Potentailly, with more b/w, you can achieve higher speeds, but you're still bound to the limitations of your CPU.
Games, such as BFBC2, are multi-threaded, which means they benefit greatly from multi-core CPU. Increasing your CPU potential/power will improve your gameplay quality more than increasing your RAM frequency.
As far as the GPU goes, they make considerable differences over on-board chipsets, but having the best card available will not guarantee an increase in FPS, rather it will improve the quality of your display. The commonly overlooked variable in this equation is your monitor. Flat panel CRT is not the same as LCD. LCD is not the same as LED.
The quality of a monitor is commonly determined by the refresh rate. Most monitors don't refresh higher than 60Hz. Because of this, most people find that reducing the screen resolution yields better FPS performance because there are less pixels to refresh, thus yielding more FPS in return.
As a personal example, I play WoW. I had an AMD 939 Dual Core Athlon x64 CPU w/ 2 GB of dual channel memory, and a 7600GT (mind you this was three years ago). I was experiencing an average of 30 FPS in areas that weren't heavily populated. I upgraded to a socket AM2+ mobo with a Phenom II X4 Quad Core CPU and a GTS 250 GPU and 4GB RAM. My FPS is now 60-70 in heavily populated areas.
1. upgrade mobo to an i-series or AM2+/AM3
2. get a quad core
3. keep the GPU
4. keep the RAM
5. adjust your resolution