Linux is also available as OSX replacement (or for G3/ G4/ G5/ PPC/ PPC970 in general):
Yellow Dog -
http://www.yellowdoglinux.com/
Gentoo PPC -
http://www.gentoo.org/
The nice thing about Linux on PPC is MoL (Mac on Linux). It's no virtual machine like VMWare (no hardware emulation), but a native speed OS9 or OSX on top of Linux PPC, and it's possible to use OS9, OSX and Linux on the machine AT THE SAME TIME. Check:
http://www.maconlinux.org/
Another nice thing about MoL is that you can use OSX on non-Apple PPC's (like PegasOS, MorphOS, Motorola PCC and IBM PPC workstations), some of 'em are cheaper than Apple's hardware, and they use standard PC parts (eg ATX boards). A lot of hardware that is unsupported on OSX is supported on Linux/ PPC.
Linux works on almost _any_ hardware out there, except for recent Silicon Graphics MIPS: x86, AMD64, PPC, Sparc, MIPS, 68k, Power4, Hitachi SHx, Itanium, Alpha, ARM, xScale... heck, it even works on IPods, Nintendo Gamecube, SEGA Dreamcast and Sony PS2!
<font size=-1>[ This Message was edited by: wsippel on 2004-04-16 10:57 ]</font>