I built a small, quiet, and powerful home theater frontend for about 500 US dollars. Below are the parts I used. I purchased the items via Amazon Prime in late January 2013.
|Processor||Intel i3-3225 with HD Graphics 4000||$134.99|
|Motherboard||Gigabyte LGA 1155 MOBO||$104.99|
|Case||M350 Mini-ITX enclosure||$37.85|
|Memory||Samsung 2x4 GB memory||$46.98|
|Disk||Crucial m4 128GB SSD||$113.79|
|Power||Kinamax AC Adapter 12V 6A||$10.73|
My previous frontends were Zotac IONs with nVidia GPU. They are still fine HTPCs but I wanted something with a little more horse power. I am pleased with the performance of the i3 and HD Graphics 4000.
Ubuntu 12.10 is the operating system. I will mostly use XBMC with the PVR Addon for MythTV. I will occasionally use the standard MythTV frontend software instead of XBMC.