Go into your Linksys & make sure UPnP is active. Also make sure it's active for LW, LW's menu bar, Tools>Options>Advanced>firewalls. See
Linksys UPnP setting (click on link) as yours will be similar.
You shouldn't go without any firewalls. Deactive XP's FW & configure the 2nd one; *
Configuring Norton Internet Security