If you have a few wireless networks in or around your home or office that you use, you can easily prioritize which one your computer connects to first in Windows' Control Panel.
If you'd like to arrange the order in which your computer automatically connects to wireless networks, just hit the network icon in the taskbar and click "Open Network and Sharing Center". Once the Control Panel window opens, hit "Manage wireless networks". From here, you can move networks up or down on the list by selecting them, then right-clicking on them and choosing "Move up" or "Move down" (where the top of the list is the first network your computer will connect to). It's simple, but pretty convenient if you have, say, a Verizon MiFi or something similar that your computer keeps connecting to automatically when you're at home. Check out the video for a walkthrough.
Change Wireless Network Priority to Make Windows 7 Choose the Right Network First [How-To Geek]