Did the USB ports ever work while running Windows Vista?
Did it come with Windows Vista installed or was it XP and then upgraded to Vista? If so, did they work with XP?
If it has worked with Vista in the past, you are getting to the point where you need to do a physical inspection of the ports (you probably knew that already
Try to look at it with a flashlight from the outside before opening the laptop. See if there is anything in there that looks out of place or if anything about the jacks seem loose or wiggles at all.
If it has never worked under Vista, that may be the problem and you'll need to see if PB has drivers for it for Vista. You'll need to know the model number (sometimes hard to find on PB laptops if you don't have the original documentation) and go here...
Hope this helps