With regards to your dilema I have the following to add

Keyboard

In the laptop world only 2 manufacturers IMHO produce good keyboards IBM with the Thinkpad range and more recently Apple with the powerbook range. Now if you do much typing (Programming for me !) then this is really important infact one of the most important considerations beyondbattery life. So a warning the IBook really lets the team down on the keyborad front, last one I tried was truly crap.. In fact my recent laptop purchase was a 12" Powerbook (maybe I'm biased) and have been really pleased with it. Having said that I dont cut video on it, although I might try.

I did however used to cut video as part of products I used to manage. What I used to like then with editing was a special keybard customised for the job (with the shuttle control stickers etc..). Thus you might want to look at getting a keyboard and customising as approriate. Also I found an external jog shuttle was really hand also (I guess you can still get usb type controls but it's been a while since I looked).
The idea of an external Firewire drive could also help alleviate your issues with the slow powerbook drive, but you might want to check with teh powers that be that capturing/editing using a firewire drive combined with maybe a dv camera also on firewire would work without adverse effects.

Just a few points worth considering
I will certainly take a look at the book

regards
Al