Two answers for me...

Personal email : I use web based tools (gmail, ISP webmail and hotmail) but also use Outlook Express at home as a kind of storage email device.

Work : Outlook 2003, Outlook Web Access, Push email on my HTC mobile phone (with WinMobile).

I have found that the syncing of Outlook contacts with my mobile phone a fantastic feature and the ability to send and receive emails while mobile is great. However, Windows Mobile is terrible operating system for a phone if you want to use it to make or answer calls!

DB