What do expect the evil hackers to do to your ReplayTV?

Make sure you have DMZ (demilitarized zone) disabled on your router. If you are still concerned, put Zone Alarm on your PC. It is an excellent program, and catches incoming as well as outgoing connections.

There really isn't much more you can do to protect your ReplayTV, nor is there much danger to it.

On a side note, I would recommend that you get the latest version of Ad Aware and run it to remove any spyware or adware on your computer.

-Biscuits