I can't say if there is a speed increase, as 3.4 was the first drivers I ever installed for my Radeon 9700 Pro, however while running with these drivers there ARE serious framerate issues under Half-Life. The 9700 Pro seems to produce framerates of 50-60 most often, 70-80 more rarely, and 100 in isolated circumstances. While playing Natural-Selection, while commanding, the speed dropped to 20FPS.
System is an AthlonXP 1900+. Previous card, GeForce 3 original, produced much higher framerates at the same resolutions and settings.