533mhz. Really!?

I'm not sure what you mean by that. Do you think that the CPU is 533? If you do, that's the max supported bus speed of the P4 which is high compared to AMD's forthcoming 333MHz.

The SB51G cost $320 from mwave.com and I bought the P4 2.4GHz (533MHz bus) for $189 from newegg.