Suggestions on Training/Certification?

About a year ago, with no previous training or experience, I was given a Win2000 internal LAN for 80 users to handle, along with all hardware and software and users – the whole shebang.
I have learned a lot through MS KB, tech forums, books, etc. but there’s a lot I need to know. No one here knows more than me now.
I work for non-profit – worthwhile purpose but little funds for this sort of thing.
Suggestions?