i have
an ibook g4 1.42ghz, all pushed to the max specs, and it just didnt cut it. i just got an imac g5 2 ghz and it blows it away.
if you need the laptop, either a used powerbook, or a macbook PRO, the regular one might not be enough.
you need an external HD, and DIGI is limited in compatibility. in order to daisy chain (laptops only have one firewire in) it has to have an "oxford 911 chipset". i found out the hard way, through 2 RMA's. FANTOM Drives supports it, ONLY the firewire ones, not the combo or USB.
As for apple monitors- the prices are not worth it, i dont think. check out newegg.com and get a decent monitor there. expect to pay 200-500, depending on your size, widescreen, pixels etc.
The ibook is ok for tracking. no problems at all. however, it is limited in processing power when it comes to mixing, and i kept having CPU limit errors in pro tools. thats my setup now; if i need to go, i take the laptop and track it, and mix it at home. WHen im recording at home though, i just stick with the desktop.
I dont like Protools on pc, its just not as simple/stable as on the macs. im using a pc now, but i wouldnt for anything else
Macs are more money for a reason; INTELLIGENT design

everything you plug into the firewire or usb ports just works... no drivers blah blah blah, windows problems etc.
the warranty covers alot, as long as you dont drop kick your computer, your pretty much covered. you can extend it at anytime if you want too.
its just like learning how to use a pc again, back at square one. you'll catch on fast though. i went from no mac skill, to now i can diagnose and fix all sorts of problems on macs, in less than a year. it feels very weird the first time you turn the new mac on though, im warning you. you feel power and simplicity at your fingertips as the hair on your back stands up.
i should get a check from apple for this... i'd make a great sales rep huh?
..wait i am a sales rep, just not for apple lol...