New Lappy?

I've been looking at my computer lately, and considering the five years of quality service it's given me. Still going strong, with only a minimum of upgrades (more RAM, a bigger hard drive, and ditching Windows 98 in favor of XP Pro). I have been able to keep Windows going strong by minimizing the eye candy, using anti-virus and anti-spyware programs, and generally maintaining a vigilant watch over it. Still, the 800 MHz Pentium 3 can take a while to crunch through audio editing and mixing, and the desktop format is not particularly portable. So I've been giving a decent amount of thought to picking up a laptop of some sort, probably one of the more lightweight ones. And since I've been getting more into audio recording as well as graphics stuff, I'm strongly considering purchasing a Mac, due to their proficiency in those areas. And I realized that I'm not enough of a nerd to really want to use engineering software on the road. (ABAQUS analyses on the plane, Mathcad calcs at grandma's.... I don't think so.)

So before I present the two Macs I am considering. One is very small, the other isn't small, but it is the lightest lappy I've seen with a 15" screen. What do you think? (Click the pics for a spin-around view):

Apple 12-inch PowerBook G4. Only 4.6 lbs, with an 80 GB hard disk and SuperDrive.

Apple 15-inch PowerBook. Slightly faster processor than the 12-inch, with more ins and outs and of course a bigger screen. Downsides: weighs another pound, and retails for another $500 (ouch).

in the player: Simon & Garfunkel - The Best of Simon & Garfunkel