Did you make sure you plugged it into the green slot!
Even though I don't see a relation between the following suggestions and moving the PC, it doesn't hurt to try. Just make sure it is not muted. Make sure that the default audio out device is set and not "Not Available". Maybe a failed shutdown before you left the house made xp revert back to previous settings before the drivers were installed.
Basically check the normal stuff. Then we will go from there.