Please help me choose the best Upgrade!!

Hello I need a bit of help. I would like to upgrade my system a little bit but don’t know my best route. I mostly play FPS & RTS: CS:S, C&C3, COH…
This is my current system build:

ASUS A8N-SLI
AMD 64 3500+ Manchester 2.2GHZ (939)
EVGA 7600GT (580MHz)
Corsair XMS 1GB DDR400

I don’t have but a little bit of money $50-$125 to upgrade. I believe I have 4 options:
1. AMD X2 4200+ 2.2GHZ $90
2. Another video card for SLI $80
3. 1GB Ram $55
4. 2GB Ram $110

Thanks for your help. I am not ready yet for a complete system upgrade.

I would suggest going for the ram aswell...not sure how much of an improvement you would get with sli. Don't bother upgrading your processor. I'm running an AMD 64 3400+ (939) and I mostly rely on my ATI x1800xt 512mb and the 2 gigs of ram to do all the work. I've gotten away using a Sempron 64 3100+ (754) on my gaming rig and I would still outperform friends' comps that are dual cores (mainly cuz of my OC'd videocard ). I recommend first trying out the other gig...dual channel should help. If your not satisfied with the performance, I'd prolly save up for an x1950xt...those things go for like $160 now and they outperform any DX9 card out now (dont quote me on that...lol)...dont bother with DX10 cards now...we still got a while for the games to catch up...