I'm in one of those Apple laptop moods again

Why the hell don't I just buy a PowerBook G4. Cheapest model is $1500, and it's fine.
light, small, cool os preloaded, no temptation of running windows, supports most of my favorite unix apps
I sell this heavy desktop-replacement for like $900 or so, and I only gotta come up with $600 (which I'm probably close to with all those uncashed paychecks). Shipping is free!
I'd wait till tiger (nick for OSX 10.4 i think) comes out in less than a month, but after that...why the hell not?