Connecting to managed switch on win 7

I bought a new managed switch (ZyXel gs1910-24), and can' get windows 7 machines to connect to it. XP Machines seem to connect OK, and the switch gives it an ip address and allows the computer to access the web interface. But when I connect on machines with Windows 7, it doesn't seem to allocate an ip address (according to ipconfig), although the connection light on the switch is solid.

I'm kinda new to managed switches - in the past I've just used routers and dumb switches. Is there some quirk I should be aware of?