I have a Treo 700p (Palm OS... Windows Mobile is the devil).
I run
AquaDiveLog on it, and my Uwatec computer beams data directly to it over IR. It syncs to my desktop software at home every time I sync the phone/palm.
LOVE the combination. It's good to be able to enter misc notes and details directly into my dive log between dives, while sitting in the galley or car. Then I can flesh out the entries at home, later... if I want. And meanwhile, I always have my entire dive log on my person at all times... but if I ever lost my phone, all the data would flow right back in just by syncing the new phone to my computer.
My Treo doesn't dive with me, however. It stays in the boat or car, usually in my waterproof mask case (tupperware sorta box).
For Windows Mobile, Uwatec offers
TravelTrak CE, but I've never used it so cannot offer any advice on it.
All of this software is free, btw, and works for any Uwatec Smart series computer, or manually if you have a different one. I believe AquaDiveLog can import from Suunto somehow also, but I've never done that so no promises.