I think you can manage great with Macintosh software and hardware.
1) to manage the interface towards the different public users you can
use At Ease - an Apple software product that are included in most Apple
bargains
2) in order to make presentations of material - audio/video or other
types types of interactive presentations also in exhibitions you can use
the very easy to handle ProView from e-magine (www.e-magine.com)

As a solution for hardware use the 'everything in one' - Macs like
Performa 5200, 5300 and so on. I suppose you by now can get these
computers for around $1.000.
John