The point is, with an identical system except for the graphics card, the 9600GT will win over hte 9600GSO in EVERY CASE.
its the classic tennis ball test: if you drop a ball from 1 metre, then THROW a ball with a red dot from 1 metre, does that prove the red dotted ball is better? NO! the variables must be the same with a SINGLE constant, or as few as you can manage.
in the OP's case, his computer probably had a slightly slower cpu, less RAM, a different RES... the possibilities are endless. to get an accurate representation of one thing vs another, there must be no variables except the ones being tested.
end of rant.