What would be a good choice for an external HD to provide server storage and playback of video/audio files (mix of HD/SD, and AAC and Apple Lossless) for use on a single TV?
Will you be recording TV to this drive, and if so, how many simultaneous streams?
Besides local playback, at that TV, by the mini, how many other devices around the house will routinely be accessing and sharing this content?
Will this drive be sitting right out with the mini, visible and audible, near the TV?
I'm concerned about going too cheap (I found a WD 1.5TB at $105)...Thoughts?
My main thought--instead of buying a self-contained commercial product, like a WD MyBook, buy your enclosure(s) and drive(s) separately: 1) it can often be less expensive, 2) give you better warranty protection and 3) it's worth being able to open up your enclosure to get at your drive without voiding the warranty.
One thing I can guarantee--however much space you think you may need now, at some point in the future you will need more. Plus, have you thought about how much space you need for Time Machine and bootable backups in addition to the space for media?
When you choose bare drives, another thing to consider is the warranty return process--some manufacturers are difficult to deal with, some, like WD, make it very easy.
I am looking at the OWC Mercury Elite-AL Pro Dual...I second the OWC Mercury Elite AL single or dual drive enclosures.
I agree with both Buick and Geo, these are nice enclosures fairly priced--but I'd buy them diskless--at the moment their dual USB JBOD enclosure for $49 is attractive. Then shop for the best price on bare drives to fill it from Amazon and Newegg. ($49 is what I paid not too long ago for an aluminum JBOD dual drive enclosure with 1) hot swappable drive trays, 2) a 40mm fan and 3) internal power rather than an external brick. It's a USB AirDisk enclosure at the moment, with two Samsung EcoGreen F3 HD203WI 2TB 5400rpm drives inside.)
A case with a Firewire 800 port will deliver the best performance with the mini (rather than USB)
Sure, but at greater expense. The questions the OP has to ask are, are you doing anything that benefits from the "best performance" and is the difference in price worth it? The USB/FW400/FW800 version of that dual enclosure from OWC is $97--seems reasonable to me--if I were buying a first enclosure I'd probably go with something just like that. Firewire and Macs are still glorious together. But the second enclosure I bought would be a dual USB one.
I was a firewire and fast drive snob in the beginning, too, years ago I wouldn't touch USB with my home theater Macs and always had good luck with firewire daisychains. (A holdover from the notoriously poor USB performance on PPC Macs, I suspect.) At some point I started adding USB storage and you know what, it's very reliable with Intel Macs and works just fine for most demanding home theater tasks. The thing to remember is this--in the typical HT, you will be CPU bound before you are disk bound.
Drives marked with an *Energy label are slower, power-saving models that may not keep up with HD video bit rates.
What HD video bit rates? Maybe if you plan on editing footage that you shot with your professional HD video cameras...but...
I've had 6 or so different "Green" energy-saving 5400rpm drives in regular rotation around my house for a couple of years now--over slow local USB and even slower AirDisk enclosures--and I assure you--they are plenty fast enough for playback of the "HD" video you're most likely to use in a home theater--that of broadcast HD TV and blu-ray rips. The inherent limitation is the interface, not the drive: a 5400 drive won't even break a sweat before real world USB bandwidth is saturated.
Most commercial Tivos and DVRs come with 5400 drives--and can handle recording two HD streams while simultaneously playing back content. Will a 7200rpm drive handle typical home theater stress and movement of files a little better? Yes.
But, any 2 drives in a fanless aluminum enclosure will get warm...two 7200rpm drives in a fanless enclosure will get hot and may also be noisy, which may not be a good thing if your enclosure sits right out in your living room.
Green drives, on the other hand, have lower idle power and can run very quiet and cool. So, unless your editing footage from your Red One at home for your first film school project, these low power drives can have a lot of value in the home theater--don't dismiss them due to fear they can't keep up. Drives are so mature now that you really don't have to worry.
That's a round about way to say I largely agree with Geo and Buick: for a first enclosure, go firewire--and one of those USB/FW400/FW800 models with an Oxford chipset would be perfect--but for a second enclosure, for backups and additional storage, don't be afraid to go USB or buy bare OEM drives from Amazon and Newegg, some of them Green, to save money.