I'd say two things....
Get as much memory as possible, Adobe loves memory.
and
Don't get a Powerbook. The hardware is ridiculously weak, there's a reason that in a few months Apple will be replacing their entire laptop line with Centrino. The G4 cpu in the Powerbook is barely any different than the G3, which I believe was introduced at around the same time as the original Pentium, it's quite outdated. For a while Apple at least had the low power thing going, but now Centrino has that.(the G4 cpus wouldn't be too bad if they slapped a faster memory bus on them though, but they're still using a single channel 166mhz bus)
A couple last things, hardware wise the only real choice is between Centrino and Turion based systems. The Centrino systems should perform a bit better in Adobe, but they're also more expensive generally.
Oh, and besides getting as much memory as possible, a 7200RPM harddrive would be nice. If the manufactuer doesn't offer the upgrade, you could get an upgradable laptop and add it in yourself.
Also, memory is much cheaper if you buy it yourself and add it in, rather than having the company do it.
Edit: Oh yeah, I was thinking you wanted a mobile notebook. If you don't care about weight, size, battery life, and heat, then for all out performance an Athlon 64 notebook will be better. The Turions are only available at the same clock speed as the Pentium M processors though, and they generally lose on a clock per clock basis.(notebook Athlon 64s lack dual channel, plus P-M has 2MB cache compared to 512KB or 1MB on the Athlons)
Athlon 64s also have the advantage that they can upgrade to 64 bit windows when it ever comes out(I don't count the current release as it has very little support), and a 64 bit Adobe should be faster than the 32 bit version. 64bit theoretically could also support more than 2GB of memory, but I doubt any notebooks actually will.