It is not quite as easy but I think u can update from the onscreen menu (no external display is required) so u could just take your avr up by your router and plug it right in and navigate thru the onscreen menu to do the update.
However, you will likely want to be able to use the internet radio feature or perhaps the network streaming on the 3808 so you will want to set up a connection to your computer and the internet. I use the linksys wireless gaming adapter: it only supports WEP security though, but you can buy a newer model with dual band wireless n and WPA for about 70 bucks. the one in the link is about half the price. I will say that I had a difficult time getting it all networked up with it though.... but now it works flawlessly.
http://www.amazon.com/Linksys-WGA54G-Wir...40523853&sr=8-1
