I really do not consider Windows desktop PCs a viable route for a school. I work in a secondary school that has recently got rid of 100 PCs and replaced them with simple terminals (net bsd based I think) and 6 citrix servers. The maintenance required on the terminals is minmal, at least as good as well set up RISC OS machines, the start up time too is very good.
Obviously you still have the standard windows baggage to deal with, but that's only on half a dozen machines. The biggest mainenance overhead we have is fixing the windows machines that are used as terminals.
A local primary school also uses our system.
My acorns access them well via my ADSL at home, (especially with the RDP client working in a window)