Let me first by saying I'm in need of help and here is my current rig:
AMD AM2 Quad Core 9500 (stock)
Asus M2N-32SLi Deluxe
Corsair XMS2 6GB
Seagate 500GB 7200RPM
XFX 8800GTX x2
Windows Vista 64bit Home Premium
Dell 24" Widescreen Monitor
Now I know by today's standards that this rig is extremely underpowered. However, for as much gaming as I do now it should handle everything fine.
I do however run into several issues which I'm not certain of. One of them being...
That I play World of Warcrack, and in most zones I average 30fps in major cities I average 7 fps. This is with most setting set to mid range, which personally I feel is ****. But it makes it manageable.
Others have recommended me putting my old Dual Core Processor in because its less likely to kill performance or to change my CPU all together. At that point tho I was considering a new Mobo and intel i7 chip.
Something is wrong. You should be able to run warcraft at very high resolutions no problem with that rig. You should be able to max almost anything out. You should be able to run crysis on very high at a decently high resolution. I dunno whats going on with your rig but it needs help.
Did you dissable the TLB bug fix? You probably had to upgrade the BIOS to support the 9500, so it probably has the TLB bug fix which kills performance. Since B3 stepping CPUs (i.e. the 9550) are free of that bug they don't have to deal with this issue, but the first Phenoms like yours do. The newer nVidia drivers are somewhat optimized for multiple threads so it probably wouldn't help you much to put in your older dual core CPU. If you're old CPU was a 6400BE or something then you may want to try it.
By the way, you were correct in thinking that I had to upgrade the BIOS in order to get the CPU to work. However, it does seem that I have increased FPS slightly, but not to what I expect. I want balls to the wall FPS, hence the reason why I built this PC a little over a year ago.