It would work. The module is also EDGE-capable and you'd get pretty decent speeds. My Sony Vaio SZ has EDGE only and I'm using it on Cingular with great results for mail, surfing, etc. I can't detect a huge difference between EDGE and EVDO from a Verizon ExpressCard.

Dell will unlock the modem for you so you can use it on T-Mo (if indeed it does have a modem). Just call support and tell them you're headed overseas and need the subsidy lock code.