<< What rogue1979 says is true and unfortunately not widely appreciated by users.
I've done benchmarks where a chip clocked to 733 (fsb133) will do as well as at 950 (fsb100). Not all games do, but most do. Quake III results correlate well with the majority of other game benchmarks.
I am talking about 1024x768x32 here. You have to have a very fast processor to make it worth playing at 640x480 applying fsaa or other image tweaks, compared to a naturally decent resolution. >>
You should remember there that the 133MHz FSB on the slower processor makes things a lot closer then MHz alone would indicate.
It really does depend upon what type of game it is and the settings applied.
There are entire genres of games and many many games that aren almost entirely processor limited, while there are also quite a few that depend mostly upon the video card especially at 1024x768x32bpp.
In the end, I'd personally prefer the faster processor... because a faster processor will benefit you in virtually anything you do. While the difference between a GF2 Pro and a GF3 is extremely minimal in most areas besides gaming.