I'd suggest taking your desires, budget, and requirements, and make a post in the hardware Section of the XBMC forums.
A simple NAS enclosure is your best bet. I was looking at them a while ago and the Synology enclosures were well priced while stil having good specs. WIreless N is enough to stream 720p from multiple sources, but can often struggle with 1080p. You can slo set up a cheap and/or old motherboard, cpu, ram, and hdd as an adhoc NAS and shove it into a closet
Check out the
XBMC Forums for lots of good info on this stuff. Plus XBMC is a wonderful program for watching and listening to various media.
Me, I crammed my old quad core CPU into a smaller, component size-compliant case with a few harddrives, adn store about 3000 TV episodes and 400 movies on it. Hardwired with gigabit NICs and cat6 cables. XBMC is very godo at sorting media and grabbing episode info/art from IMDB adn TVDB.com, and it has ALL codecs built-in. I suggest the "Transperensy!" skin.
If you wish to to an actual PC for the media and don't want a Windows OS, Unraid or Ubuntu are your best bet.
You can also find tiny HT-centered PCs that can be foudn cheap, adn work very well, like these:
http://www.newegg.ca/Barebone-Mini-Computers/Category/ID-3
PS - for ripping your media, Handbrake is free, has many options, and is pretty easy to use. Or use Imgburn is you wish to keep the menus intact.
PPS - if you do everything from scratch, I'd suggest a ANS for storage, and either pre-built HTPCs or those media players like Boxee, EDTV, Popcorn Hour, etc. for each television.
Abram do you know if third party programs are still required for XBMC to access an iso file? When I first started doing that you had to use something like Virtual Clonedrive. Unrelated, my drive with all of my HD rips recently died, which prompted me to start actually buying blu-rays. Pretty excited for that since I was able to pick up quite a few this week at Walmart and Amazon for 4 bucks each brand new.
Um no, it'll play them on its' own. I had my Dark Knight BD50 ripped and it added it to the library adn played. Though blu rays have an odd time with PC's. the only program I've ever found that does the menus and such properly is Total Media Theatre 5, which I've set as my external player for BR discs on my HTPC. But I prefer to rip my blu ray to /mkv using MakeMKV or Handbrake. They end up at 15-30gb, depending on a few variables.
Not sure which XBMC build you used, but big changes came with Eden (v11.0), and more are on the way with Frodo (v12). You can find nightly builds for Frodo - it has a rebuilt audio engine that support Master Audio format.s not ath it matters if ones' receiver doesn't support it.
Back on topic: Grave, have a look at [url=ipazzport.com/]ipazzport.com[/url]. THey have a nice array of very excellent mini-keyboards. some have gyro-controlled mouse control, some have a trackpad. They are cheap in price, well-made, and have insane battery life. Essential for any HTPC. Other companies make HTPC-centric keyboards, but these fit on your pocket. (FYI have the KP-810-18A, which has and IR remote on the back side. bought mine from China for $24CAD, shipped)