so 1Gb per child does not seem overly generous to me.

Fair 'nuf gov. We never have enough disk space :-)

RAID is a must, but IDE gives us a lot more Mb for our money than SCSI, but maybe at the cost of performance/reliability?

IDE devices, being cheaper, are certainly slower, and in some cases less reliable. These drives are going to be hammered. IDE devices are designed for home machines and don't stand up to the continuous use they get in servers. If you want a Tbyte, I think RAID/SCSI is pretty essential. Some SCSI disks are identical to their IDE equivalents except for the interface, but many are built using better technology (and last longer).

Nevertheless, it seems to me that even a modest hard disc can outperform the 100MHz ethernet to which the server will be connected.

Assume nothing. A single IDE drive would be a bottleneck. It's to do with the head seek times while possibly hundreds of files are open simultaneously, not the tranfer rate. Plainly multiple drives allow the OS to thread accesses much more efficiently (this was always a big selling point for Novell servers which handle such matters particularly efficiently). Plainly money is an issue. Please feel free to laugh: I think a 10 Mb network is insufficient for a Windows stations doing logons and accessing files from a server. I ran a network which was originally set up this way and it was SLOW. I think you need a mix of 10/100 to the stations, depending on what they're loading, and therefore you certainly need a backbone which is faster. I think a single 100 Mb net card would be a big bottleneck. Ideally you need a 1 Gb backbone with switches taking you down onto 100 Mb local segments. The server gets connected directly using a 1 Gb card. Failing which, with a lot of fiddling, you can use 2 or more 100 Mb cards in the server. You can physically subnet, or use IP subnetting to divide traffic. You are talking about lots of traffic and to plan for less might be economical but a mistake. My experience is that schools hammer networks much harder than most businesses do - schools push the envelope much harder despite the lack of budget. Prices for this kit are Mega but no longer astronomical. -- ******************************************************************************** All mail sent and received may be examined to prevent transmission of inappropriate attachments and certain obscenities. Wellington College does not accept responsibility for email contents. Problems to postmaster@wellington-college.berks.sch.uk. ********************************************************************************