No with older cards you can notice a diffrence. If I read right, than your saying to me that I didn't notice the frame rase in CSS with my TI 4200 when I was @ 20 to 32 in a hard rendering map...
Even my X1600Pro I notice a big diffrence in games when I overclocked. It just Depends on the overclock he gets. If he overclocked 5Mhz than you won't notice a thing but 50mhz or higher you can see some frame rates go up.
Anyways here is hes picture of hes current overclock. He's Stock speed is 270mhz -> 310mhz = 40mhz overclock. it shouldnt really be much faster in UT game that he has, but once he get's high he should see some games run faster