Intel don't make the fastest Pentiums. Cyrix and IBM do. Cyrix designs them and IBM makes them, and the PR200 is currently has the best price performance rating.
The PR200 actually runs at 75MHz externally and 150MHz internally, but because it has a better cache, a longer pipeline and better branch prediction and optimisation it goes a faster than an Intel Pentium running at 200MHz internally (though only 66MHz externally).
There are a few catches. The floating-point instructions are noticeably slower, but only if you do a lot of floating point work. You probably don't. And no, Excel users don't count either. If Excel is using floating point, the extra speed of the PR200 for the non-FP instructions makes up for them. It might matter for games, however. In this case buy an Intel P166 or wait a few months for the P55C, which has some of Cyrix's optimisations and full-speed floating point (and MMX if you choose to believe that cart-load of hype is worth having).
You may wonder why I don't suggest an Intel P200 for games? It's simply because I don't like the chip. It multiplies its 66MHz external clock by three to get 200MHz, which is too much. The core may run quickly, but how can it access its code and data through a 3:1 bottleneck? I don't believe it can, not properly anyway. And when it can't get its instructions fast enough the pipeline stalls and the whole thing slows down. It is faster than a 166, but only by 5-10% - you really wouldn't notice. Considering the price is more than double it looks like a waste of money to me.
Anyway, back to the catches with the 6x86. Catch number one; it has special voltage requirements so not all Pentium motherboards are suitable. Those designed for the P55 as well as the P54 (as most of them are) are quite suitable, and manufacturers of newer boards are keen to support non-Intel chips anyway.
Catch number two is Windows NT 4.0. Unfortunately, just before they released it, Microsoft got a pre-production 6x86 system for testing and found it didn't work. It was, I'm told, a fault on the motherboard but with just a week to go Microsoft's fix was to check for a 6x86 and if found, to disable part of the cache at boot-up. Not unreasonable, but wrong, and it made 6x86 systems run rather slowly. Fortunately they test against the chip's revision number so if you get a chip with revision 2.7 or later it won't do it. Only old stock will be an older version, but if you're running NT 4.0 you must check.
Catch number three is that the PR200 runs at 75MHz externally, and Intel's motherboard chipsets are only rated at 66MHz (I wonder why...). No problem as VLSI and SIS both have 75MHz boards which seem to perform just as well as Intel's, if not better.
Intel is having to play catch-up on this one. The Pentium Pro is cumbersome and expensive and Cyrix have shown that performance is possible without brute force. AMD are also attacking from below with a PR133 design which threatens to be scaleable in much the same way. Early on in 1997 Intel will strike back, but until then the IBM PR200 is the best bang-per-buck you can buy. How do I know? I got a sample of all the current Pentiums, AMD and IBM/Cyrix chips and a universal motherboard and I timed them all.