Yep, this is my one and only name here. I'm Smilin all the time (hehe) so you may have read my posts elsewhere (shuga shack, q3world or something).
I WILL however agree with that mystery person on one point.
A higher framerate will allow you to jump higher in quake 3. I don't think it makes you move any faster in any other respect but it does allow you to jump higher.
Why? Because when you jump your flight path is a parabolic curve. It's not really a curve, but a very close approximation. The curve gets broken into a number of straight line segments based on how many times per second your cpu calculates your position. At something very, very low like say 8 frames per second, your flight path will resemble the top half of an octagon. At 125fps it will almost be a perfectly smooth curve.
If you jump for a ledge you can make it if your cpu calculates your position above the ledge at the moment you reach it. At a lower fps this becomes unlikely to impossible.
For you that still don't believe and have the graphics card to pull it off, try this:
Quake III Arena, map: q3dm13.
Go find the mega-health and try to jump to it (from the front, not walking around to the ledge above). You probably won't make it. Now turn the fps cap off: from the console type "/com_maxfps 125". Try again. If your graphics card has enough muscle you'll make it every time.
Another interesting thing...try it while carrying the quad damage. The quad puts a bit of a glow around you and puts some additional blue polygons around your weapon. If your graphics card is marginal you won't make it in this state because it's slowed you down just enough to screw up your flight path.
(This post got long...my bad.)
Short answer: No never posted here before under a different name, but yes having a better video card can allow you to move better in fps games.