Thanks! To follow up (I just received my bill for Jan/Feb)

I set my connection to use Q2Net - it seems to have worked, with airtime charged for calls made, but no data usage charges. My phone doesn't seem to be making random calls to the internet anymore, but I haven't re-enabled avant go, and I set my weather panel for manual update only (my two suspects). I also installed IP Dashboard - its a very cool little program that tells you when and how much data is being transferred and through what kind of connection.

Now if I can only fix my stupid Activesync that thinks my device is incompatible about every 5th time i sync, but thats another thread...