Right what I am trying to achieve sounds simple..full VPN access with a windows 7 client into my network.

Currently I utilise the VPN supplied by the Grid, which gives me full access to my school's grid allocated subnet. That would all be fine, if my internal network actually used that subnet. How I have my school's network set up is that everything is in a private address range and all clients that require internet access go via a Forfront TMG firewall/proxy (obviously this has two network cards, one in each network). The network contains only the outside NIC of the TMG server and a switch.

How I get around the problem now is to simply allow RDP through a specific port on the TMG from authenticated users with an IP in my VPN range. This works fine in most cases, but I have specific need for full VPN.
I have no idea how I can actually achieve a scenario where from the client end, I would connect to the Grid's VPN solution and just have full access to my internal network, no messing around. Any ideas?