Need advice in choosing a broadband plan...

Hi,
I need to be telecommuting to my work in the United States from
India for 3 months.
I am trying to pick a broadband plan from the providers available
there.

>From what I am seeing, there are no unlimited usage in most of these
plans. They all have been restricted by a GB value in there. They
range between 2 GB to 40 GB. Additional download will cost me per Mb.

My business requires me to VPN into our company network for about 15
hours a day for 5 days a week and access our network resources
including source control, outlook, communicator (for instant
messaging) , SQL server and other corporate file systems et all .
Can someone give me a feel for how much usage will I require for this
kind of access?
If I need to post it in a different newsgroup, please let me know.

Thanks
-Siva