Hugh, take a look into a raspberry pi
http://www.mcmelectronics.com/product/83-14631
$35 + $5-10 for an 8GB SD card and you have a mini-computer at your disposal. Add another $10 for an optional case (or there's even a pdf available for a homeade box that you can print on card stock and keep your unit in there).
http://www.raspberrypi.org/archives/1310
I have been looking into one since I tend to use my laptop connected to my tv to view streaming videos over the web. I'm just not sure the raspberry pi can do view all mpeg, mkv, and various format avi's from files or just about any website, like I can do on my laptop. I just haven't taken the time to do much reading, but it sure does seem like it.