i don't know about that, i have a amd tbird 1.1 ghz, geforce 2 gts, all tweaked out and i only got a score of 4800. if a 4200 and a p3 700 only score 4100, i think the reasonable upgrade would definately be your mb and cpu first. videocard after. not only that your overall system performance, browsing, etc will improve as well.
Athlon XP 1.58GHz | MSI KT3 Ultra2 | 256MB DDR PC-3000 | GeForce 4 ti4200 64mb @ 310/533 | IBM 120GXP 40.0GB | Det. 41.09 | DX 9 RC2 | Win XP SP1