Possible Home Media Server?

Should work, i have run media files off slower machines without issues. Just remember it will not have allot of power(so its file server only[no encoding] and you may as well fold on it ).

Also the 100megabit lan will be a bit of a bottle neck.

Just make sure you have enough cooling for your hard drive in that small case. 24/7 operation can get warm.

For the price i almost want to try one of those, but no TV out makes it less useful for me.

Faster LAN will help you transfer to the machine faster. its an extra cost that is only worth it if you find it takes too long to send files to it. This is your call, if you do, look for Intel's Pro low profile card.

http://www.ncix.com/products/index [...] ture=Intel

the normal lan(100 megabits/sec. closer to 80 in reality most of the time) will be ok as long as you are not streaming multiple HD streams(ripped blueray 30+ megabit per stream). if you just watch DivX/XviD they only use 0.5-2megabit per second. MCE recordings and DVD's take 4-10megabits per sec.

As i said, i did do the same thing with a slower machine and it worked ok. you should have no problems.

What OS are you going to run on this?

OS is a personal choice. I had a copy of XP Pro laying around so i used that. In my case being able to install other software i use on there worked for me(I also later upgraded it to Media Center Edition and more hard drive space + new cpu). but with linux being as free as it is, i can see many reasons to use it.

What your building will be essentially a NAS(Network attached storage)

I did a quick look for a linux distro with that in mind and found this. May be worth a look.

http://www.freenas.org/