'...it also required the most extensive tuning efforts, many of which were done at a level of sophistication that would not be available to the average programmer.' I think that's the problem in a lot of systems today. Too many "average" programs are being written by too many "average programmers" - and this is why there are the problems such as memory leaks, etc. I feel too many have been spoilt by the ridiculous memory and processing speeds available in todays computers. What ever happend to understanding how functions perform and refining code to be lean and mean?

That's because you did 2 intelligent things: You got good power supplies and left the machines running. It's the constant on/off/on which causes the drives to spin up/down/up that create a lot of wear on the drives - not to mention the 'surges' when the computer is turned on.

Technically, it's not multi-tasking anyway. It's really just application switching. And the 3Gs already does that ok (ie. I can have my music playing in the background whilst browsing the web).

...is always the best. Filter only at the local network level- via your own proxy filter. Facebook is fine - in fact, it can be used to improve and extend elements of educational curricullum. Of course filter all the 'undesirable content' - but as the first poster said, dont become obsessed with stopping the students accessing anything - because, at the end of the day, they can still access it at home. Youtube and other streaming sites could cause issues for bandwidth; apart from that, just use common sense: games sites, P2P...etc. are all unnecessary. My advice (from personal experience) - get the staff to provide lists of websites they use regularly as resources, and then block out 90% of the rest of the crap. There will be some adjusting and movement in the first 6 - 12 months, but once everyones gotten comfortable with what they can and cant see / do, they'll relax into it.