We're doing some DR scenario planning which will require up to 150 users to RDP into their desktop machines (mainly running Windows XP) over our VPN. We have a 2mbit uncontended internet connection at the moment but there's scope to upgrade this and also to use a secondary SDSL line to give us more bandwidth.

Typical bandwidth figures I've seen suggest to plan for 64kbps per session, which works out to 9.6mbps in total. I'd like to know:

1. Does anyone have any real-world data which would support these estimates?
2. Are there any operational 'gotcha's that we need to be aware of?

Thanks!