T-mobile is now doing "Unlimited/Unlimited/Unlimited, So why worry about it?)
If you have a pass phrase or encryptio key, and/or have set the device so only AUTHORIZED devices can connect (I have done both) then if you shut down the PC, there is nothing that can suck data from T-Mobile.
If you leave the PC open there are a few background data suckers like Windows Update Service, but .. They will run on restart anyway so it makes no difference.
But with Unlimited.. What I'd do is watch my usage for a couple of months, IF you go over your "high speed alotment" they won't bill you,, Just throttle you.. They are not Verizon (Home of the SUPRISE billing department).
PS. I use T-moblie myself.
