Why wont my computer recognize *ANY* iPod's that I plug into it?

Ok so I'm trying to put new songs on my iPod Touch from iTunes. And when ever I plug in my iPod to *ANY* of the 4 open USB ports on my computer, it doesn't recognize the iPod. I've tried it with my brothers friends new iPod Touch and that doesn't recognize it. So I have no idea what to do!!! Is my computer just stupid? HELP!!! Oh and just so you know I have a 2005 Dell Dimension E510 with Windows XP Media Center Edition.