"Martin" wrote
| (I realise that this message might be more appropriate for America's
| comp.home.automation but I'm UK-based and, having lurked on
| this newgroup for some time, I know that there are some
| knowledgeable contributors who might be reading this.)

There is also uk.tech.home-automation and uk.tech-digital-tv

| (b) The distance from the TV aerial to the UHF distributor in the
| "Node Zero" cupboard is 30ft. If I put the distributor in the attic
| instead, the distance would be only 15ft. Would this make any
| meaningful difference to the signal quality?

Depends on the signal/noise / BER of the incoming signal and the extent to
which it is degraded by the cable. Google uk.tech.digital-tv for postings by
Bill Wright - his website has useful PDFs on multi-outlet aerial systems. He
has also just completed a 3-article series in Television magazine on
multi-outlet satellite systems.

| (d) Can anyone recommend a digital audio server compatible with a
| networked music player and a Windows XP p.c. network?

have a look at Myth for Linux

| (e) Does anyone know of a system whereby I can connect 4 intercom units
over
| a LAN?

Use a PBX. Connect the PBX exchange line ports to the telephone lines
downstream of an ADSL filter. Alternatively, VoIP telephony with Asterisk
running on a Linux box.

| Ideally, the three security cameras mentioned above should also be input
| into the distribution amplifier so that their pictures are viewable on any
| TV. This will require some sort of IR switching control to select the
source
| signal.

Modulate the cameras on different UFH channels. Most modern TVs will do both
VHF and UHF, so plenty of free channels.

| Alternatively, I could use cameras with an IP address so that I can
| view their pictures on a p.c. connected to the LAN.

Split the camera outputs between the UHF modulators (above) and PC video
capture cards, and do both.

Owain