Overall looks like a sensible build.
How about an HDD and/or SSD? I assume you will need at least an HDD if you are going to be doing a lot of recording. SSD would be great for your OS and programs, but maybe unnecessary if it is going to be running 24/7 and you don't anticipate booting up a lot.
The case looks cheap and won't blend in with your theater components, but this is just personal preference. Unfortunately, true HTPC cases run a bit more expensive, so you would have to adjust your budget.