Jane,
     We are in the middle of searching this one also.  Our Cisco rep has
recommended we investigate the following tools:

MOSY
SMICng

     He also recommended looking at the comp.protocols.snmp SNMP FAQ Part 2 of 2
at

http://www.landfield.com/faqs/snmp-faq/part2/

Specifically Paragraph 2.30.04

     Haven't gotten to the first part but will tomorrow.  Just saw your note and
thought it ironic that it's hitting all over the place at the same time!

          Best of luck,
          Bill