Windows 7: Computer offline/online status

Is there a program that works with windows 7 that have a webinterface and can monitor if a computer is online or offline, just like logmein can?

I'm going to use it on an exam system.
Users boot up trough usb in a windows 7 tiny version using winbuilder.
So need an easy program that can monitor if a computer is online or offline trough a webinterface to i know that the students uses the exam system and not their own.