Sure you can use two networks, but you will need some manual setup (in cmd) to route the trafic to one or another.
Choose start then type
cmd and enter
First things first, you will need to understand your configuration, to achieve this, type
Use right click, and choose/mark/select (or something alike) select all the text press enter to copy. Them past it in a new notepad window or some other text editor
Repeat this step with the another network attached.
Remember to note also wich text is from what network.
The most fundamental lines are that following the 'Active routes:' specially the value under gateway.
The gateway server is the primary server that your computer is attached to, it is the server that helps out when your computer needs to reach any other service/website/etc.
Well this is the end of a first step.
The second one will need your intervention in a more active way:
You will need to discover, and note down, All IP addresses that you need to access by one network or the another, to achieve this, you may need to type:
And note down the IP address to them, it's also a good idea to repeat this command within some minutes to make sure that this address isn't changing.
Another way could be talk to your network administrator to get his/her help with this.
As soon you have all this IP addresses, you should try, plugging in both networks, and type:
one last time
Now your first lines after that 'active routes' should be compared to your notepad notes, the gateway responsible by your very first 0.0.0.0 route is your primary connection, so you do not need to take any actions to use anything that need this connection.
To each service that you need that is only accessible by the another net/route you will type
route add <IP_ADDRESS_OF_SERVICE> MASK 255.255.255.0 <GATEWAY> metric 9
Where gateway is the server from the non primary one
Then you already can test if this service is accessible.
To know more, take a look at: