Diagnostics

[redhat at buglecreek.com]

We run a lot of Redhat servers an on occasion we run into systems that
appear to have a hardware issue.  Does anyone have reccomendations of a
good diagnostics software we can run on these systems to quickly
determine if we have hardware issues (memory, cpu etc)?  Maybe a live cd
with diagnostics?  We are looking for something apart from the standard
Linux tools (/var/log/messages etc).  

Thanks