swap the iBook's hard drive with a 5400 and you'll erase this important difference between the two. I have a 1 ghz 12" iBook and just changed the hard drive to a 80 gb 5400 Hitachi Travel Star and it has made a huge difference. Way more room and a much snapier speed all around...
it's been posted many times but once again the instructions can be found at pbfixit.com. It wasn't too hard. If any of you iBook owners haven't upgraded your HD yet, you should. The biggest tip I have is to have a plan for all the screws before you start. I bought a pack of tiny zip lock bags... you can find them in the craft section at wal mart... and at each step with screws I put them into a bag with a small peice of paper with the page number and the color corresponding to the screws (some steps have screws with different sizes and pbfixit differentiates each with different colors)... once everything was taken apart and the HD was in it was very easy to put everything back together because there was no confusion...
So...

get the iBook, upgrade the ram and HD and ride out the intel transition with a stylish, durable, and highly capable notebook!