What kind of G3 is this? Apple doesn't support running OS X on anything older than the Blue & White G3 towers.
And while I'm not sure, I think the newest version they can run is OS 10.2. Macs have a long service life, but trying to get this thing up and running any modern programs is likely to be more trouble than it's worth.
Core i7 920, 3x2GB Corsair DDR3 1600, 80GB X25-M, 1TB WD Caviar Black, MSI X58 Pro-E, Radeon 4890, Cooler Master iGreen 600, Antec P183, opticals