You want to spend "000 for an X2 4800+? You my friend are crazy... Why don't you instead spend the money on 2 cards for SLI seeing as your CPU is quite nice as it is? I mean that would probably increase your gaming capacity a lot more...
You dont need ECC RAM with FX series CPU's, only Opterons. That said, whilst the FX will probably perform better based on current stuff, anything written for a multithreaded environment, including hyperthreading, would run a LOT faster on the X2.
Quote from Seqo: Ahh, just read up: socket 939 got rid of the necessity of Buffered ram for the FX series processors.
As has been said though... might as well go SLi for $2000... then my graphics card would overtake my cpu. 512 ram 1 ghz core clock. it think 1 7800gtx is fine. but my cpu is weak.
3500+ is ample for todays games, as they more graphic intensive than anything else. Personally, Id go SLI before shelling out for either of those CPU's, 1) It will give you more of a performance increase and 2) When you your CPU really COULD do with an upgrade, there should be more support out software wise for the X2, meaning you wont have to sacrifice something no matter you choose. With CPU architecture changing, you're best off waiting for it to settle down or you could find yourself in the position a lot of Socket 754 users did when the A64 first came out.
That said, get a 2gig TwinX kit for RAM...with the figures you are talking you should be able to find RAM and an SLI configuration that won't blow the budget. Your RAM is the weakest part of the system, and the CPU is fine.