I would attempt to do a "factory" reset of the router before upgrading any firmware. If the router is not working correctly, then there is a chance to completely "brick" the router when it "flakes" out during the updating process. I personally seen a D-Link router that required a few factory resets before it stabilized.
Also, if you do do a firmware update, connect an Ethernet cable from the PC to the router. It might not be stated up front, but never update via the wireless network as the update will "break" the wireless networ and may reset the configuration back to factory default (thus "destroying" the wireless network.)