HTPC = money pit haha. I run the following setup.
I have a Windows Home Server (WHS) running mymoives.dk You just put in your dvd/bluray and it rips them to the hard drive. The WHS has 6TB of harddrive in it and ablut 70% full, need to add a few more
Then I have another pc that is acutally the HTPC. It runs Vista Premium and media center. With the media center I can hook into the WHS and stream movies threw my xbox 360. The I use media center extenders on the other tvs in the house so basically any tv in the house (even bathroom) can stream from the WHS.
With Media Center you can record tv play music basically its a pc so you get the idea

They are very easy to manage now adays with the current software. Well worth it if you watch a lot of tv or movies. But like i said its a money pit. If you get into bluray you need higer end pcs becuase you need to transcode the blurays on the fly to play on most tvs.