Originally posted by: tadmaz
My noobish guess is that I need to set the FSB

RAM scales, it's at 1:1 right now
Are you sure it's at 1:1 right now? That would put your PC2100 running at PC3200 speed, which is unlikely.
FSB is 200 "quad pumped" to 800, your FSB is right where it should be for that CPU.
You <i>should</i> be at 3:2 as Stormgiant said, which would put your RAM at 133 (which is 266 effective after taking into account that it's DDR)
If you are really at 1:1, consider yourself very lucky that your memory overclocks so well. But somehow I highly doubt you're at 1:1.
Use CPU-Z or aida32 to give you more insight into what your board is actually running for it's RAM/FSB/CPU speeds.