The PB has a disk drive, and IMO, the screen is easier to use than the widescreen on the lenovo or the wind (it's too narrow). The keyboard is luxurious. My dad, depression baby that he is (1st gen) recently bought a 12" g4 1.07 ghz ibook with 768 megs of ram, and it is surprisingly usable to surf the net, etc.
He lucked out, and got his (with a cd reader and 30 gig hd) for $245!
I've hacked an msi wind and lenovo s10; but for me, the features of my 1.5ghz 12" pb wins, hands down.
That's exactly what I was thinking. Plus with the disk drive, it can be easily upgraded. If I do get a PB, I'll find a 320 GB HDD for it.