Server Maintenance

I just bought a server running win2000 server, thats
managing five machines… I need to know how can I
sustain long usage of my server. I never turn it off, its
probably been running for three months straight.. Its a
celeron 1. someting…with two fans , im a little scared
that it just might stop work one day. It was also bought
this year. I need to know the best maintenance
practices