What format does the G4 case use? What power supply will fit? I like the case too. Very well designed.
No Mac user in his/her right mind buys RAM from the Apple store. That's like buying RAM from the Dell store. Overpriced.
A Mac iBook is underpowered, and the screen is way too small (12"

. A PowerBook laptop is too expensive for what it does, but it is feature rich, with even Gigabit Ethernet built into the top model. New versions are coming out soon though, so if you're truly interested then wait a couple of weeks to see what's in store.
However, I think the best deal is a PIII Coppermine laptop with 14" screen, CD, floppy, ATI Rage Mobility 128 video, 128-256 MB RAM, 6-10 GB drive, Li-Ion battery, built-in 56 Kbps modem, TouchPad, and Windows 2000. Ultra stable, and pretty damn fast. Good deals seem to be the Acer 521TE and Dell Inspiron 4000 among others. With an extra LAN card, it should be way less than US$2000.