Howtogeek posted a guide about changing the wireless network priority to make Windows 7 choose the right network first
If you've got multiple wireless networks or you've got one of those dual-band Wireless-N routers that have two separate networks, you might wonder how to tell Windows what network to try to connect to first. Here's the explanation.Change Wireless Network Priority to Make Windows 7 Choose the Right Network First
For example, my home network has a lousy Verizon FIOS router that's only Wireless-G, and so I've got a separate Linksys dual-band wireless-N router hooked up inside the FIOS network?the only problem is that we've got 3 separate networks going, and as you can see from the screenshot, the lousy YDQ48 network is above lhdevnet in the list, so Windows tries that one first.