You made no mention of cooling. You might try making some cooling improvemnts. But, probably the main thing holding you back is the memory. PC2100 using a 1:1 ratio is only rated for 133 MHz. Obviously, most will do better than that, but 150 MHz is probably asking too much out of it. Try backing off on your memory settings a little (like using a 5:4 ratio).
I'm running a different board (see sig) but I'm stable at default voltage @150 mhz w/intel retail box fan. I have pc2700 cas 2 ram, though. That might be the difference. You might have a buddy with better ram let you try his? If it works, "out with the old and in with the new!"
Those memory ratios don't make sense... 1:1 is the same as 4:4, maybe look again. I might be wrong about the 4:5 and 5:4 ratios, it might actually be 3:4 and 4:3 ratios. If so, use the 4:3 ratio which runs the memory bus at 3/4 the FSB.
The difference between your selected Vdimm and the actual figure indicates the power supply is overloaded. I would recommend a 350W sparkle from newegg, and some real ram if that doesn't fix the problem. Corsair XMS PC3200C2 all the way if you're paying for it.