Hi all, thanks for your comments. There are pieces of information that make some of the advice redundant, I believe.
Although not located within line of sight, my electrical cabinet is a narrow room running parallel to my hall, connecting the lounge and dining room (about 3m long). My server cabinet sits within this and my wall mounted LCD screens (LG xxLH3000 series) are both within 5m of the cabinet location. Each Screen has a 100mm sleaved hole behind it, through which I can route cables.
The intention is to run a HDMI and RS232 cable to each screen from the MD's. It would be awkward to mount the MD's behind the screens as they are wall mounted. Given the relatively short length of these cables I'm hoping that I wont have a problem (indeed I currently have scart and component from other sources, and spdf going from the TV to the receiver, which is also in the electrical cabinet).
Below the TV is an aperture in the wall, acting as a AV equipment cupboard (this aperture opens up into the electrical cabinet). In the lounge this contains my receiver (Onkyo TX-SR706), centre speaker, and sub woofer. The cables route up from the rear of the equipment into the heart of the electrical cabinet, and through the hole in the wall to connect to the screens. Normal USB cable lengths will extend into this aperture to make USB connected devices within the line of sight of the user.
Consequently I don't think I will have a problem connecting the equipment, it merely becomes a question of controlling Linuxmce without physical access to the media directors for the respective screens. If this can be done exclusively by nokia 800's / browser based orbiter then I'm golden. If not I need to know whether I need to connect a remote control (and locate an IR tansmitter/receiver where the remote can "see" it), or whether I can connect bluetooth mouse/keyboard to the media directors. I want the "easiest" to use control system for a lay person, so my preference is nokia 800 > remote control > keyboard/mouse.
By keeping the media directors and core in the electrical cabinet I can run them with decent airflow (hence choosing the asus board with active cooling) without noise being an issue. I chose the tyan dual network board as the core (the only atom board I can find with two NIC's onboard), and assumed the lack of nvidia graphics wont be a problem for a pure core (not a hybrid). I will be building a custom case housing the three motherboards and three power supplies. The intention is to put 3 off 1TB drives attatched to the core, with any further requirements for storage met with NAS. I'm assuming one DVD drive attatched to the core will allow me to setup everything. The core and the media directors will be attatched to a KVM and screen in the electrical cabinet for setup purposes - will this be a problem to then unplug the electrical cabinet monitor after setup and connect to the LCD screens, or will I be able to connect the VGA (to the KVM) and the HDMI (to the LCD HD screen) simultaneously during setup?
I appreciate these seem trivial questions, on the face of it, but my experience is that the devil is in the detail and forewarned is forearmed.
I also have some portable LCD screens (1280x1024) behind which I will mount the acer single atom computers for distributed use around the house. I've wired multiple CAT6 sockets to each room for this purpose (amongst others).
1) I use a DT360 to control everything. There is no need to have remotes or keyboards or mice except when you're browsing the web or working in KDE. There is a bug, which hopefully will be fixed, that does affect this sort of "orbiter-only" setup - basically, the OSD pops up for no reason, and you can't clear it from the Orbiter ( http://svn.linuxmce.org/trac.cgi/ticket/549 )....
I presume that I could substitute a Nokia 800 for the DT360 that you have in this role, and I get the full functionality (bugs not withstanding)?
Thank you for all your help.