Start with this http://www.amazon.com/Zotac-IONITX-90-Watt-Intel-Motherboard/dp/B002BA5IHC/ref=sr_1_3?ie=UTF8&s=electronics&qid=1283483342&sr=8-3

Get a small case, some ram and a small laptop HD. You could do SSD if you wanted really quiet. Then install xbmclive, once setup, configure it to use hdmi. I have three HTPC's based on that board and they can be run fanless and with the dual core and the Nvidia VDPAU i'm doing 1080p over the network to my NAS.

I've tried the WDlive, the seagate, AppleTV, xbox360... none are as flexible as xbmclive.

I worked in a datacenter that was two blocks from the harbor. The datacenter is on the second floor, but what the hell do you do if you're in the building and there is a flood, or if you're at home and have to get to the DC? It reminds me of New Orleans, but that didn't stop them from building it.

http://www.readynas.com/

I have a Pro and a Duo. Based on debian, community hack support, all around good deal. I couldn't build a tiny pc with as many features and space for the price. X-RAID means you can keep expanding as drives get bigger and cheaper.