Managing movies would be nice but unless I could store everything I owned in HD I won't bother, and I can't as we'd be talking multi-terabytes
Streaming TC to multiple clients - now that my friend is a bloody good point and one I hadn't considered back at the beginning. I've got a quick and dirty RF2 output to my TV in my bedroom but that's obviously not as flexible.
Multi-terabytes is a problem? I've been building my system for a couple of weeks and I have the same issue. I own more than 300 movies, and at 7gb per that's a lot. Since I don't have a budget I've been using parts laying around my place (and a couple of my friends' places). I'm up to 1.1 tb on 9 drives. I have 3 more 80 gb drives to add, but I'm waiting to see if I can find anything bigger. If I had any cash, I'd pick up the Seagate 1.5 tb drive I saw on Newegg for $189. Or maybe 2.
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