I have a curve 8900 and a 500mb down internet plan. I am wondering how much bandwidth does windows live messenger use if i have it running all the time on my blackberry ? Not on wifi, i know that would be free.

I want to use it, but don't want to be staring at a monster bill next month.

Thanks in advance

An individual message is only going to be a couple of kb worth of data, provided you don't attach pictures or other media. But your data usage will also include incoming messages.