LinuxMCE/Pluto Home can do this, according to their websites. However, I don't have any experience with it personally, so i don't know how well it does everything.
More importantly, that's hardly a consumer-grade solution, which is really what Adams is talking about. ("consumer-grade" meaning relatively affordable, reasonably straightforward to install and control, etc.)
linux is free dude.. and runs on commodity hardware. The installation.. is a one time process, so if you sold boxes with it already installed would not be an issue, and the controls are very intuitive. Linux mce is very comparable to boxee.. something you install to use as media center software. If they can figure out boxee, I don't think mce is that far off.