Win 7 x64 pro
4gb DDR XMS corsair
I have a very simple two dimm Intel motherboard not sure model number at the moment.
My question is, what is the best place to start in the upgrade process? I use my computer mostly for Work (remote desktop, office, email) but also I play Battlefield Badcompany 2, World Of Warcraft, and Rift. I wouldn't mind better performance in my games
I was thinking of going with a new mobo/cpu/ram combo and getting one of the X6 Phenom Hex core CPU with 8gb DDR3
Getting a 6870
What would yield more performance for my shooters and mmos?
Trick question! Your mmos would benefit from a cpu upgrade or a good overclocking. 6 core processors aren't a great buy in terms of gaming. They are designed to handle many processes on all cores but gaming only uses 1-3 cores thus wasting half of your processing capability. If you wanted to go the cpu, mobo, ram route I'd go G.SKILL Ripjaws X Series 8GB (2 x 4GB) and i3 2100 and P8H67 for a total of $280.
Your shooters would benefit more from graphics (hence trick question!) a 6870 is a great card and a 450 is a pretty terrible card for gaming. Depending on your budget which from your post seemed to be spend either 200 on a new card or 350ish on a system. You could pick up Sapphire 5770 for $115 ($20MIR) ($5 shipping).
Thus a total of $400 for system upgrade and graphics. $200 for 6870. $280 mobo/cpu/ram