The Wing is pretty much all T-Mo offers right now in the way of Windows Mobile Pocket PC phones. There are plenty of imports on the market you could use as well, but they do cost considerably more than a Wing with a 2 year contract.
The Wing can certainly handle MS Office documents and tether (albeit at EDGE speeds). At 201MHz, it's not one of the faster PPC phones, but it's adequate. If they have a live one at the store, try it out to get a sense of the speed.
-------------------- Lisa Gade Editor in Chief, MobileTechReview