Usually a 250 watt p.s. is all that is needed for a PIII, PII, or Cel. If there are going to be alot of hd's, cd-roms, geforce cards and so on inside a tower case, then maybe a 300 watt.
P IV's will need a special power supply because they use 3 different power connectors on a pIV mainboard that uses RAMBUS ram. Suggest min 300 watts.


------------------
If Hannibal were a pc support tech,
He would invite the stupid user over for supper.
"Tonight, I shall feast on stupid user's brain" ffffttffftftftfftft