I had to submit this query over several posts but, at the time, AOL kept reconnecting itself.
Can anyone advise me if it is worth spending time trying to get a 1998 Mesh PC working, or should I not bother?
By the way, having opened it up you have never seen so much dust!!!! Looks like Miss Haversham's wedding breakfast. It is safe to use an ordinary vacuum, obviously taking care to not actually touch anything with the nozzle, but holding close enough to (hopefully) clear the worst of it. The dust on the Pentium 2 fan is really thick.
I clean mine every 3 or 4 months with a hoover and a small selection of brushes. A radiator brush is particularly good for the intricate gills on a Zalman CPU heatsink. I avoid compressed air like the plague simply because the propellant aggrevates my asthma.