2 nics 2 wans

I need to hook up a PC with access to 2 WANS with different ISP. The PC needs to access both networks, both ISPs but each for a different tasks. It needs to use one ISP for regular internet access (browsing, msn, etc) and the other one just to access a specific program that will download some messages.

How do I separate these tasks? Is there a way I can tell the nic to just access the internet to check on the messages for a specific program?