SNMP Help Please?

Hello,

I am new to SNMP and I am trying to get my servers to be monitored from my
XP machine. However I am not able to do this for a lack of knowledge in a few
areas.

1.) I don't think I am getting a clear picture of what a community string is?
2.) I have tried public and Private but I get no response with these. AS to
say the programs I have used cannot retreive any info an give me errors.

I installed the SNMP on both Server 2003 machines however no luck

Thank you
Joe