VPN hogs bandwidth

I have a few MS Small Business Server 2003 setups. I am just exploring VPN since everything is so easy on SBS 2003. When I connect to any of them, the normally 2.5 Mbps of RoadRunner goes down to around 170 kbps.
This client needs 4 people into the quickbooks files remotely simultaneously. SBS is limited to 2 remote web workplaces and, I think, 2 remote desktops. I would prefer they just have the advantage of the VPN to use just the data and not bog down the server with remote control sets.
Thanks for the help…