1. DVR - Expanding on DewChugr's recommendation, this is amazing if you actually like TV. I took an old PC, installed Vista Home Premium and a TV tuner on it, and now have a full blown DVR. I also have a useful app called webguide (free), which allows streaming/recording scheduling through my phone. If you have an Xbox 360, you can sync the two and stream video,etc.
I use XP Pro and gbpvr. I've got a dual tuner so I can record HD and/or standard cable. I built it on a dell P4 2.4 server with raid. It's so quit I fon't even know it's running. Only bad thing is no PCIe. I can view local movie guide, have photos, vids, music etc on there. I put on iTunes so then I can easily access my shared library on any computer. I can't program from my phone, no internet, but can through any browser. I can also, depending on connection watch live tv or recorded shows over the internet.
I'll have to look into webguide. What vid card do you use and is it PCIe or AGP?
It's so cool skipping the commercials and all without shelling $$ out to tive or comcast.