izit worth? well it depends..
i had been using both powerbook and ibook G4 (1Ghz) and it really fulfill my desire as a programmer whose addicted to tv shows and do some shell programming. With ibook g4 (1Ghz) you can :
- use leopard ( i upgrade my powerbook to 2gig of ram and 250gig of hdd already

)
- install office 2004 (2008 not recomennded)
- watch tvshow, movies,hentai blabla (except for mkv files, which contains h.264, damn laggy)
- play with ilife 08 (except for imovie 08 which need more cpu power)
- use adobe product ( i use cs3 without no problem)
- play with UNIX
- show off your ibook
but with 1.8K u can get Compaq C700 (intel core duo or amd processor) also capable of :
- use leopard (yes, please read osx86 project)
- use xp ( although no support from hp websites, must find the driver yourself)
- use Linux,freebsd or any other Unix osses that u like, just create dualboot or tripleboot.
as i said before, it depends on your needs..