SL and usage restrictions

http://www.bt.com/broadband/bb_info.jsp

I use the 2MB version of the above broadband connection for internet access (or rather, I pay for 2MB but my line supports just 512k, so that's what I get). You will see that there has recently been a 15GB a month "usage restriction" put in place, and a charge for those users who go above that. How much data transfer does SL use, on average, for each hour you use it? Should I expect big bills from BT if I continue to go in-world, or is it nothing to worry about?

Gah, Charlotte, do you have any idea of the INSANE amount of money it costs me to play SL?
I'm on a 512k DSL that has a 3 gig cap...
The most I ever consumed was around 7-8 gigs. You should be safe with 15, don't know how much you play.

Since the entire Second Life world is streamed to you in real time, we don't recommend using network connections that charge you for bandwidth. If you do so anyway, I highly suggest turning network bandwith (in Preferences) as low as possible.