There's plenty of options out there when it comes to PDA phones and there's services like Goodlink (aka push e-mail available in the UK).
For example, Vodafone has it's
own push e-mail solution and according to their website it's compatible with the following phones:
# Motorola MPx220
# Qtek 8020
# HP hw6510
# V1620
# VPA Compact
# V1240
# V1640
# Qtek2020i
# Nokia 9300
# Nokia 6680
# Nokia 6630
# Sony Ericsson P910i
The ones in bold are touchscreen PDA-style phones. Dell don't make PDA phones unfortunately.
All of the above PDAs can be used to make regular phone calls. Some are more phone orientated (SE P910i) whilst others are defininetly for those who want a PDA that you can make the
occassional phone call on (V1620).
This is only the tip of the iceberg though. There's lots of different e-mail solutions out there and an equal number of PDA phones.