I use a Linksys WRT54G router with DD-WRT, which has an option to specify arguments to the router's DNS server. Adding address=/wii.com/0.0.0.0 will prevent the Wii from accessing wii.com, which, I assume, is where it gets its updates. (I haven't tried testing it, I don't want to accidentally upgrade my Wii.)by SheeEttin - Offtopic