What should I look towards - RasPi, Arduino/etc, something else?

OK, so I'm looking to set up a homemade home-cinema type control system (actually for some lecture rooms and the like, but the concept is pretty much exactly the same). The industry standard controllers are humongously expensive, so difficult to program you have to pay contractors to do it (heck, you can't even buy the upload util without going on a pricey course first), not massively reliable, and on the whole don't do a very complicated job with a standard level program.

I initially thought about setting up a touchscreen with a RasPi and a suitable add-on interface board to fully replicate the current experience, as that would be rather cheaper than the existing setup even so. However, given the simplicity of most of the setups, I can probably do it even more simply.

But, being something of a noob to this, I've gone a bit crosseyed looking over the vast array of available IO boards, and even started wondering if an RP was maybe over kill (!) and if a microcontroller might be better. The programs, after all, would for the most part be so simple that I was initially tempted to try doing it in Sinclair BASIC with an old speccy and switches wired to the key contacts until I realised that it probably wasn't going to be able to bit-bash information down the serial lead at 9600 bps using POKEs.

So, my requirements:

* upto 3 infrared outputs per system (absolute max of 6 with a twin room shared system)

* usually a single relay output (max of two)

* 2, maybe 3 RS232 3-wire serial outputs (9600 or 19200-N-1) (again, maybe 4-6 max). Having one or more of them able to work bidirectionally for status polling would be nice, but not essential

* input of at least 4 push switches, realistically 6 or 7, and a maximum of 16-20 using some kind of matrixed system maybe with a separate component-level IC on breadboard.

* possibly at least some of those switches being light-up type so the light indicates e.g. power on/off or selected input channel

* alternatively connection to a simple LCD touchscreen plus suitable programs or programming capability for such

* option: ability to automatically slave one system to another by hitting a button on the "master" to link them, thus avoiding complication of twin rooms sharing one controller but still being able to operate as one larger, easily controllable space when the dividers are open, possibly automatically triggering a certain command sequence that will automatically change device channels to make that work right.

* option: RTC for simplistic scheduled operations

The button controls would at the simplest level be e.g. a power toggle, screen up/down and a cycling input select, extending up to a possibly overcomplicated arrangement with direct selection of 4 to 5 channels, power on and power off, volume up/down, and regular DVD/VHS controls (play/pause, stop, forwards, back, up-down-left-right-enter, menu) and a re-sync button.

One of the trickier things might be trying to sample the IR codes that are needed, I know this can be sort of bodged using a receiver diode and an extra-high-frequency sound card, but I don't know if I have access to such a thing so it might be good if there's a way for the system itself to "learn" the codes.

The RS232 ones aren't quite as difficult :) nor the relays!

Total memory needed would be quite low, which is why I think the RP (and potentially expensive boards) may be overkill, but then again, Arduinos and their ilk don't seem particularly cheap in small quantities either. In neither case do I know what sort of interface would be needed to provide both these ins and outs, or the sort of programming that would be required. Like I said, I imagined doing it in BASIC (it doesn't need anything more sophisticated than that, programatically!), and I have at least sorted out the low level concept of what the system needs to do, but am unsure how you'd actually do it or what to buy/download/etc.

And yes, this is somewhat melding the abilities of two different types of controller that we have installed. The cheaper pushbutton ones are actually alright and aren't TOO expensive or hard to program at a very basic level, but are too limited for widespread installation, in terms of their onboard I/O. EG only seem to have 1 or 2 IRs, a single serial, no relays etc. To get that we have to go up to the much more expensive and sophisticated (and unprogrammable) ones.

Switches would just be commodity Push-to-make types with transfer labels, in a cheap box... but I've toyed with the idea of using a modified USB or PS2 numpad with the unwanted keys removed and blanked, or one of those subminiature HTPC keyboards...

Any ideas, pointers, tips?

Thanks :)