Well, if you want a laptop, then go for the iBook (obviously...), but there have been loads of rumors that a new Intel-based iBook's coming out eventually. Just hold on for a while. If you have the money for a Powerbook or, better yet, a MacBook Pro, go for one of those. But the Intel-based processors, after testing, show that on native and universal programs, they can run up to twice as fast as a PowerPC G5 processor. But, the G5's are slowly dwindling, as Intel takes over Mac. My opinion: Wait for the Intel iBook to come out, by then there will be more software designed for Intel macs, as Rosetta can either run REALLY well or REALLY slow on Intels.
But then again, that's just me. I have an iMac Intel Core Duo, and I don't regret it. I'll never go back to PC again without having at least one mac with me.