I'd experimented with forwarding my POP mail to my mobile in the past, but it never really worked for me.On the other hand, I've become completely addicted to using GMail, it's now the only email client I use. Handily, Gmail is now rendered in a mobile phone / PDA friendly format, including conversion of PDF to HTML and display images. Just point your phone's browser to: http://m.gmail.com
One really neat feature is 'reply by phone' as well as using your GMail contact list to make calls, so now I don't need to synch my contact list -- GMail handles it for me. Nice.
Now they just need to implement the long awaited Google Calendar and have mobile access for that, and I'll be set.