best graphics card for 6BA +IV

ok, as the subject really.

Specs are

Celeron 466 overclocked to 500 something! ;p
Soyo 6BA+IV - BX chipset I believe, I think it supports 1x/2x agp so needs
to be a card like that. Was thinking Geforce3 Ti500 as these can be picked
up for a couple a quid, will that work?

Also can anyone explain the voltage problem as i understand that the mobo
wither supplies too little or too much can't remember which.

I know the systems really old, but I just want to play original half life
and CS/TFC reasonably well. I will eventually upgrade at somepoint, maybe
even to a P3

thanks

Russ