OK guys, I'm thinking of getting this phone next week on T-mobile's Web'n'walk plan at £7.50/month (I'm in the UK).

Just need to know how much data transfer would it be doing with the average Googling, Excessive use of SATNAV, WI-FI etc.

This plan allows upto 1gb transfer/month - would this be enough?
There are other plans which allow 3gb, and 10gb of transfer...which one would be best for me?