Is it just me or is the question a little confusing compared to the answers? I think it would make more sense if it was: 'What do you use as your main media storage device?'.
Personally I use Windows 7 as my main media server running SageTV with 15TB of storage space, however I also run WHS2011 in a virtual machine for backing up my client machines.
I answered the question exactly as asked. Do I have external media storage? Yep. What OS is on that computer? WHS v1. Now, I've actually pulled all my media out of the drive pool, but it's still on the same computer.
Assuming I'm reading it right, for you, the answer is actually "no" because it sounds like you store all your media on the same computer you run the front end (SageTV). So, your storage is internal.
unraid fanboy here.... I answered linux since I assume the appliance option is an off the shelf nas appliance.
I have 3 external USB drives (currently totaling in 4 TB) dedicated to media storage running into a USB hub into an Apple Airport Extreme Base Station. The drives are shared through the router itself. I guess this is the "Yes, other" category...
Currently have a 16TB WHS V1 for backups and central storage of all my video content. I keep looking at WHS2011 but I don't want to deal with RAID and the drive extenders are still in beta.
Another unRAID user here. Currently at approximately 21TB and counting (actually a bit less than 20TB when you subtract the overhead). Been running it for about four years now and loving it. Extremely reliable and uncomplicated. Pretty much set it and forget it.
You could argue that you're also using internal storage, since it's internal to your WHS v1 box...which is why I thought the initial question was a little confusing and ambiguous.
Anyway, I think I answered the question correctly since the storage is on my SageTV backend server, not the front end.
Hehe... I do see your point. But, I always take this to mean external from the primary playback device, whether that's a 360 or HD300 or a full HTPC. Otherwise, you wind up with a USB drive being the only thing that's not considered internal.
Buy Cheap Home Theater Systems from DHgate