if you get a powerbook with bluetooth down the road, you'll like the isync-ing of address book - if you have a bluetooth phone.
I don't know that any of those handsets are bluetooth, but if you call that number I gave you and ask them to help you arrange the upgrade, maybe they can give you a credit for the difference.
Shoot, you could ask them for a sony ericsson t637 and be well off.
the siemens s66 would do you nicely as well. They aren't listed as being free, but ask anyway.