Are you referring to Activity Monitor in SSMS in 2008? If so, then you will need to run a trace to collect the different queries that it runs and probably grant permissions to the user. Ultimately I have to ask why someone would need to use Activity Monitor and not be part of the SYSADMIN group? :ermm:
David
@SQLTentmaker“He is no fool who gives what he cannot keep to gain that which he cannot lose” - Jim Elliot