Password Audit tools

[Jeffrey M.Miller CISSP <jmiller () acumeninfosec com>]

I've used Internet Security Scanner from ISS and really like it's 
ability to pull users from NT domains and test common passwords, such 
as username=password, password=password, etc.

I've considered purchasing the consultant version of l0phtcrack LC5.

Has anyone used LC5 and can anyone compare it to ISS?  Also are there 
any OpenSource tools that can do these sorts of checks?

Thanks

J_