350 is not a heavy load unless all of them want to chat together or have to go through an e-test simultanously. IMHO any current server modell will do.
As you have already experienced once, leave some space for future wishes, expansion, etc. Check this for example http://moodle.org/mod/forum/discuss.php?d=6920#32597
As you have already experienced once, leave some space for future wishes, expansion, etc. Check this for example http://moodle.org/mod/forum/discuss.php?d=6920#32597