How can I manage/track the data use on a HTC Inspire? I thought this would be a popular question but couldn't find it here so if you do please let me know.

My mother just got a new HTC Inspire and is brand new to using a data plan.  Since she is worried that she might go over her cap I want to know how can she track how much data she has used in a certain time (preferably within a billing period). I am on Sprint so I've never had to worry about how much data I use. My question is: Can you recommend a method to manage/track data?

Also, I figure that apps like weather and news should be changed to check less frequently... any other default apps that should be changed to check less frequently?

Thanks for the help
NetCounter will keep track of data usage. It may not be 100% accurate, but it would be a decent estimate.