Although I didn't get any further assembly pictures after that point, it turned out that the motherboard was flakey. I don't know if it just sat around too long and was damaged or if perhaps something was broken during the construction, but it was not stable so I decided to outright replace the entire works with another mATX board: an ASUS P5RD1-VM with onboard everything. Add a 3GHz P4 and a gig of RAM and was good to go again.

After a few outings however, it was clear that at least some airflow through that cabinet was going to be required. The machine would overheat within an hour or so unless I opened the cupboard door and cranked the trailer's air conditioning up. So, I tore it all apart again and added a 120mm exhaust fan:

It is doing the trick perfectly. Not too noisy and keeping both the MB and CPU at just a few degrees above ambient.

Originally, there was a 15" 4:3 LCD TV used as the display but I decided to give that one to my daughter to use in her bedroom and installed a 23" Samsung HDTV. It is mounted with an articulated VESA bracket:

Here is what the finished project looks like:

The amplifier on its shelf. Beneath is a little UPS I put in to act as an AVR:

The outside:

One weatherproof speaker:

This project was well worth the effort. Once again, I have full access to my entire music collection plus temporary and secure storage for my photographs as I fill up the cards.