How do i connect a laptop and a PC to the internet using a switch?

How do i connect a laptop and a PC to the internet using a switch?

I plugged my modem into the switch along with the laptop and PC(using ethernet cables) and the switch into the power supply(outlet).The laptop is using vista while my PC uses XP,if that helps.
My pc receives connection while the laptop doesn't.What's the problem?What am i supposed to do.Thanks in advance.