Dell likes to use proprietary motherboards and cases so a standard atx/micro atx board probably won't fit. Not sure if you meant you wanted
to try and use that or not. I definitely recommend starting fresh with a new case.
Also you picked a full ATX motherboard. Normally people go with micro atx for an htpc so you won't need a large case.
Its a good board but overkill for an htpc. All you need is an H77 board for an htpc.
What TV provider do you have? Are you just planning on recording OTA with an antenna? Or whatever your cable Co sends over QAM?
If you have a cable or satellite and want to use that it won't work for anything but QAM that your cable co offers in the clear.
Which these days is usually maybe locals in HD and some or maybe none of the other channels, usually SD.
If you are aware of all that then disregard.
Not sure if you intend to record High Def, but it cmoes out to about 4gb an hour. 500gb's will fill up faster than you think
with HD. 2tb is where its at for DVR hard drives. I would get the biggest you can afford now instead of finding out later that the 500 is not
That was kind of all over the place but just some stuff I noticed.