I appreciate the fact it appears you are going for a particularly energy-frugal system, but I think your gaming experience would improve noticeably with a faster CPU. The X2 250 or 550BE would be big improvements, and not swill down too much more juice. Your old 690G may not support one of them even with a BIOS flash.
Speaking of low noise, I just "wasted" $7 getting a PWM fan (bgears/Xilence) for my Ninja Mini, but it's so quiet I'm running it at full speed anyway. I'll probably stick the old one in the front of that case.