http://www.racesimcentral.net/
aling-09.html
"..........Gamers - do not overrate the benefits of a
Hz processor! Every model at 500-700 MHz will perform
well for some time, and those between 700 and 1000 MHz
should last you for at least 12 months. Remember, the
key to more 3D-performance is a faster graphics card!
...."