I have a Mac and a PC (now running Windows 8).
My Mac stays connected to the WiFi very nicely, but my PC likes to disconnect every 5 or so minutes. I'm using a Microsoft USB adapter model MN-510.
Here are some odd things I'm seeing:
I'm connected to my university network, but my WiFi is set to "Off":
However, when I go to my network settings, it seems to be running: