Added the Sonnet dual 1.8 to my Sawtooth today. Installed pretty much without a hitch. A huge speed increase from the 450 MHz that was in there, however, the bus speed is definitely an obvious bottleneck in certain cases.
Still using the original HDD and that's also bottlenecking in some situations. Not sure I'm going to upgrade much more since adding too much more will really tax the PSU, can probably barely handle what it has now.
I also added a flashed ATI 9800 Pro. Worked great for about an hour, then a piece came off inside the fan and really messed it up so I put the old card back in for now. Hopefully I can get a replacement from the guy who sold it to me.
Geekbenched it for kicks and it comes in at 1315 under Leopard. Not too horrible, though I think some of the Macbook Airs come in better LOL. I think it was at 350ish under the 450MHz in Tiger.
Graphics wise, if I can get the 9800 Pro in there should be doing alright for what it will be used for (CS3 training machine, web browsing, streaming video, maybe some other Apple specific software learning like FCE etc), though it's probably not critical Leopard would be a bit nicer with it.
Cheaper, more useful upgrades for me on this might be quieter fans/cooling system. These old G4s were loud to begin with and it is more so now, though I must admit it has more of a consistent rushing air sound from the processor fans. Gotta replace that case fan I think.
Gonna sell my Mac Pro, I think, so this will be my only Mac desktop for awhile.
Anyhow, will try to update later.
Current Junk Inside G4 Sawtooth:
Sonnet Encore Duet 2x1.8 GHz
4x512MB PC100 RAM
Sonnet USB 2.0 PCI card
ATI Radeon 9800 Pro 128MB (assuming I get that working again)
Original DVD ROM whatever that was
Original 40GB HDD whatever that was think it is a slow WD
Original SCSI card (will probably remove for airflow purposes)
Original Zip Drive (may remove and replace with a HDD front fan)