I just wanted to give an update to you guys about my discovery.
I purchased a G.Skill SSD and also upgraded to Windows 7 and am now running A-10c at double the frames.
No CPU (E8500 @3.1)overclock, no GFX (HD4850) overclock, and ONLY 2gb or RAM!
Windows 7 is probably the most worthwhile upgrade you should do if you aren't already running it, and I'm an XP diehard.
I ran the win7 experience eval and my system got a 6.5 with that cpu, 5.5 for RAM, and 7.7 for Hard drive (SSD), but the most surprising thing was my GFX. It got a 7.4. Not sure if the new ATI driver is the cause or the OS, but it is confirmed by A-10C performance. It is smoooth except when the Sun enters the screen, then the frames lag. In fact I have gotten such a boost in FPS that I can now run 19x12, textures high,tssaa,HDR,8xAA,512 pit res, and shadows High at the same frames that I had when I disabled all that stuff @ 12x10 res, Pre-win 7 and SSD.
I am running 40 FPS with the above settings, but can hit 55 FPS if I just turn off HDR!
So Long story short I am a happy camper. Now I am in no hurry to buy a new GFX or CPU. RAM is my weak link and that's cheap. The SSD has also made my computing experience so much better all by itself. Oh and I did run A-10 with win XP on the SSD and the sim's performance improved dramatically. But the SSD was $200. Win7 was only $85, you decide what's best for your setup. Hope this helps someone out there.
Cheers-