Another note...
Windows 7 will in fact use to two separate WAN connections. It doesn't, however, do any active load balancing (as far as i can tell). I think it routes traffic through one connection or the other based on the IP it's connecting to. For example, if I visit whatismyip.com, it will always show the same IP address. But if i go to a different site like ip-adress.com, it will display my other IP.
Also, online bandwidth tests will not show the results of load balancing. When you start a test, it establishes a connection with only one of your internet connections, and uses that for the entire test. To truly see the result of load balancing WAN's, you have to use something like Bittorrent, which establishes hundreds of connections. This will allow your load balancing setup to distribute the connections between your two internet connections.
Finally... Whether you want to set up active load balancing with a VM, or simply let windows manage the two connections, you will need to make sure each connection is on a different subnet. So if you have two routers, configure one to operate on 192.168.1.XXX and the other 192.168.0.XXX. Configure both NIC's manually. If you rely on DHCP, they will both connect to the same network