I burn through your monthly quota in about 30 minutes using Slingbox on my BlackJack.
Thank goodness I have 4 batteries (2 extended and 2 regular) that I regularly rotate throughout the week. Remember a couple of months ago when I reported burning through 4GB of data use? This past month I "dropped" down to 3.5GB...
Personally, disabling 3G defeats the purpose of getting this phone. With simultaneous voice and data a 3G-only feature, it's worth the battery drain since I can make calls while sharing Internet connection with my laptop and watch Slingbox at the same time.
Don't let my wife know I have the following GSM-capable Windows Mobile devices:
Cingular Blackjack, T-Mobile Dash, Symbol MC70, Qtek 9100, T-Mobile SDA.