The WiFi is the best in any handheld out there (there were some reviews of palm vs pocketpc, and palms performance was 3-4x pocketpc performance).
However, ALL PDA wireless is fairly low power, so don't expect the same distances you get out of a laptop.
Palm no longer make any PDAs with built in Wireless, you have to buy the Wireless SD Card and it only works in some of the models (ie T3, T5, LiveDrive).
There are loads of email software available, I use Chattermail which is an IMAP push based solution (similar functionality to a Blackberry). Then theres SnapperMail which is your more traditional mail client and is very very nice.
The LiveDrive is a nice unit, good screen, 4Gb hard drive (makes a great MP3 player), you can even convert DVDs or movies onto it.