That's off by an order of magnitude.
200Mhz PPro can theoretically execute 600 MIPS (3 instructions per clock), assuming only high-throughput instructions are used and no cache misses. (the average IPC for realistic workloads is ~1.0 though)
The Pentium Pro is an out-of-order, superscalar processor (that started the lineage of modern x86 processors).
yeah, i just looked it up again because I started to doubt what I found the first time and you're right. Still, a good estimate of how many instructions are required to evaluate a move/position is needed and I can't imagine that would be a small number (I just moved the bishop, i still have my finger on it :) what is it attacking now, what is attacking it?), and I don't see a promising way to "factor" that across multiple positions without hardware support as Deep Blue had or the parallel circuits in the human brain.