[G4Man]

I would like to know if the G3 250mhz wallstreet powerbook processor can swap to higher processors ( 266mhz-500mhz ).

If you're talking about using Apple's daughtercards, then the only faster one that will work in your machine is the 292 mhz. Apple's daughtercards only work within the same family (233/0, 250/1, 292/1 or 233/512, 266/1, 300/1). If you go with the third party upgrades from Newer or Powerlogix, then you can go all the way up to their maximum speed, at least 458 mhz and maybe 500.