General help

Do Windows servers form arrays? For "easily handling" of 3000 students then a fast single server, with a 3.xGHz processor with heaps (2GB) of RAM, and a php accelerator *might* fall just short of "easy," but that all depends on the number of simultaneous users and the wieght of the things they are downloading . I am not a sysadmin but it seems that the sysadmins here recommend a small array of linux boxes (even just two three perhaps) would be better for these sort of numbers. 

The number of simultaneous user accessing the database is critical. Even with "3000 users", if the Moodles are being used out of class, then you might see only <100 (more like 50) simultaneous users which could be handled easily by one new server with standard specifications.

But if some of your classes are using Moodle simulantenously in a computer room (during class) with 100 terminals and a some students accessing the database for homework elsewhere, then you start to have not so "easy" (slower) handling. Server loads depend so much on the way that the Moodles are used. If you use large Glossaries or other autolinking extensively, especially without caching, then be prepared to wait a while for pages to appear.

 My bet is that at first, in the first or two year, with not all that many teachers having created courses, even a bog standard server would do, unless you are migrating a load of online courses from another LMS. It takes a couple of years before teachers have the content to use the system. If you get the best server for your budget then you can feel fairly safe in the knowledge that even with 3000 students, assuming non classroom use, a single server will probably suffice.

A single modern server will start to feel the straing with simultaneous users in the (3?) hundreds (please see Don's post), I think, In my ignorant opinion.

And as other posters have contended, Moodle is faster than other comparable LMS.

Tim