The best setup for Moodle is using the LAMP system. Linux (Operating
System), Apache(web server), MySql(Database) and PHP (additional
processing language for html delivery). All of which are freely
available from the Internet.
If your IT manager is familiar with Linux, s/he should know about the other software.
If you are looking for a test machine, you can almost use a spare server or P.C. to do your test run. You should have at least:
1Ghz CPU (I have used less)
512 MB ram (can be less, but you will have a performance hit)
As little as 20 GB hard disk. 40 GB should be more than enough.
You can almost find a used P.C. with these specs in Akihabara for about 10,000 yen . It will definitely get you started.
The installation instructions are on this moodle.org homepage. They are quite easy to follow.
It will need to be accessible from the Internet (assuming you have a firewall and/or proxy setup at school) for outside access.
You can handle quite a bit of students with this and if the need
arises, you can upgrade the hardware setup to something more acceptable.
Hope this helps ,