Go with T-Mobile and buy a Palm. If you like Palm OS, get a 680. If you have no experience with PalmOS, get a Palm 750. The 750 has a slighly lower res screen, buit it will allow you to check personal e-mail and corporate e-mail. It will sync with Lotus notes via hard cable. If your work was using MS products, it will do push e-mail without a Blackberry server.
It will also allow you to read and modify excel, word and powerpoint on the screen. You can read PDF files and there is tons of aftermarket software.
Finally, with the 750, since it is windows mobile, you can add a wifi card for $79.
Read up on the Treo line:
www.treocentral.com
I suggest T-mobile over AT&T since the per minute charges are less over seas in most locations. Also, the all you can eat data plan, including wifi hot spots, is $30/month. You can buy any phone from Palm directly, unlocked. It costs more, but you will save more than the difference in 1 year of service from T-Mobile.