+1 for Pre, I use the homebrew app "Terminal" all the time. Screen is a little small, but does the job.

No "rooting" is required, just enabling "developer mode" which is supported by Palm.

3. Outlook plug-ins don't work. This is a limitation of Outlook. The plug-in can't be the default calendar, and Outlook will only pop up reminders for the default calendar. Also, my experience of OpenGroupware's plug-in is that it is unstable.

Not true, there are a lot of MAPI plugins...some work better than others. We are currently using Oracle Collaboration Suite's MAPI connector and it is very stable. It allows shared calendar, email folders, contacts. Most users wouldn't know the difference from exchange.