Oho, now that's the difference between us! I'm approaching 5 years of using SageTV, there is literally zero chance I could get away with 1 TB - I have 1.5TB for SageTV alone, 3.5TB (usable) in a variety of hard disks.
I can't just put it on a single NAS either; i've got 1 200GB RAID1 for email/finance/digital pictures, 1.5TB RAID5 for TV, 1 400GB RAID1 for lossless CDs, and 1.5TB in JBOD ripped DVDs. That's ~12 hard disks in 4 physical seperate arrays. It'll be distributed to 2 different 24x7 PCs.
I could reduce that to 3 arrays (email/etc, TV+DVD, CDs), but that's as far as I'd be willing to go. Any more and you're crossing the streams unsafely. IIRC, a NAS is about 60W, 3 of them are 180W, add that to the 22W for the zTroller and you're well over what a regular PC would do.
Don't worry Rupp - you too will be an HTPC freak soon enough, at which point the zTroller won't be that big a deal as you may as well squish it onto your mega-file server