well he could plunk in a G4 cpu upgrade but that would be the same thing really
Unless I am mistaken if the G4 upgrade is past something like 500 or 600Mhz the bus has to be run at 66Mhz or something. G3s should be able to run high with no bus speed reduction. I think they make 1.1Ghz versions of both...
the best things he can do is max out the ram ( 1,5 gig ) or at least more ram
Blue&Whites can take a max of 1GB (256MB per slot) if I recall from the Rev 1 and Rev 2 that I own.
An original Radeon or Radeon 7000 is cheap.(try not to get a 7000 though, they are shit)There are other more expensive cards like the 9200 and I think some 5x00 series nvidia but those can get expensive.