Depends on your budget. You could make a iBook work, no doubt, but a PB with the faster internal HD, the option to go to 2gigs of ram, etc. make it much more "future proof" in the music area.
That said, the 1Ghz PB in my sig does great for recording audio via Cubase, audio manipulation/editing via Peak 4, and real-time audio processing via Max/MSP.
As for audio interfaces: M-Audio Firewire 410, Presonus Firebox, Presonus Firepod, or the Focusrite Sapphire. I wouldn't spend any less if you were even moderately serious.
Mics: Make sure to have a Shure (pun intended!) 57 or two lying around, and maybe a few 58's as well. Great dynamic mics, classic sound, great reliability. As far as condenser mics, check out any of the Blue mics, Oktava or AKG. If you buy a condenser mic, remember to buy a screen or make one out of pantyhose and a metal coat hanger.
Mic cables: Have plenty of mic (xlr) cables around, of varying lengths. It is always good to have a backup cable or 10.
Other: Don't forget plenty of mic stands to take care of your needs. Have a few surge protectors to protect all of your gear. Keep audio cables as far away (as possible) from electrical cables, as this will help to prevent electrical noise from creeping into your recordings.
Good luck with it Sammis89.