Those are real slow, like 98 or 108 mhz. I'd say don't bother... I had one many years ago (reg. 128, not TV) and it would get all weird and usually end up locking up if I tried even the smallest overclock. It would be a good idea to upgrade if you're looking for 3d performance.
Believe it or not, my friend is playing the return to castle wolfenstein demo with this card and it's not that bad. His CPU is only a celeron 500 too! Oh, BTW, this card runs at 134Mhz and memory at 125 (according to the o/c utility)