Ashcrow dude, forget about Linux on a Mac: MacOS X is SO sexy, that I want to ccrap my pants! Best GUI in the w0rld as well as the power of Unix (FreeBSD and NetBSD specifically)
you dont need to crap your pants, it so slow you can double click, then go to the bathroom (even down the hall) and crap, then when you come back it'll almost be done opening.... :-P

i have linux, mac 9, and mac x on my ibook. linux i use the most, mac 9 i use when i need a mac app. mac x i play with or use to fix linux and need a unix to fix it. (actually that only happened once, when i accidently lost my superblock and had no backups! luckly i was able to (from mac x) dd if=/dev/hda11 of=linux; cp linux linux.bk; mke2fs linux; dd if=linux of=/dev/hda11 count=1 bs=4096 and i didnt lose my files ;D but thats offtopic. anyway mac x isnt so great. it looks nice, and has a unix (but with the bsd tools not gnu :-/, but the gnu compile/install just fine so its not that bad)
honestly i prefer icewm over mac x. icewm i have more power, i can hit option to open a term, apple-tab between windows not applications.