If you want to go wireless and you can't have a dedicated PC downstairs to be your VPN bridge, then you might be able to buy a dedicated IPsec bridge which you put behind your wireless gateway. This is serious overkill.

Probably the right answer for the home network is to have the wireless be outside the firewall, and limit the incoming connection to the specific IP address and destination ports. That would mean that a dedicated outsider would be able to run emplode and see your car stereo, which is probably an acceptable (if humorous) risk.

Think of the possibilities for mischief, particularly from your friends who now know all about your potential home setup. Drive by with a laptop and a wireless Ethernet, and they can add new music, delete old music, relabel tracks, and heaven knows what else...

Maybe you really should have a PC downstairs. Rather than the WAP11 gateway, just get an old laptop or get one of those micro-case PCs. PC Power and Cooling (the Silencer folks) sell a 1GHz P3 computer in a 1U box for $1000.