The easiest way is with two VPN routers (like Netgear Prosafe using gateway-to-gateway VPN example).
That way the default gateway for all the machines on the is the same for the VPN and the internet. Once setup, to go on the internet or VPN is transparent to all the clients and the VPN is usually solid. Just turn on both VPN firewalls and it just works.
If you use a second gateway (the VMs VPN), you may need to either enter a route entry in the computers routing table to use the VM's VPN or you would need to make the VM the default gateway for the rest of the machines on the network and then have the VM route traffic either to the router for internet access or to the VPN.
VPN with Microsoft can be a large topic but Microsoft has some good articles for example http://support.microsoft.com/kb/308208
After I got some VPN routers, I wouldn't want to do it any other way. But of course that mean purchasing hardware.
Hope you find the solution that works for you.