I just had to reinstall windows xp on my computer and before i had no problem sharing my media through my router onto my xbox... but now i can't even get online let alone share my media unless directly connected to my modem.  I have windows xp SP3 if that means anything at all but anyways, if anyone has advice on how to set up my network connection so it can read my router again that would awesome....

Hey dude i had the same problem, go to start, then control panel, then search for administration, then click services, then go to UPnP Device Host and right click it then restart. this should fix it temporary until you restart your PC. then you gotta do it again to let it work thats what the problem i am having.