Choosing what tools to use

["Michael Condon" <admin () singulartechnologysolutions com>]

I have been evaluating BackTrack3 tools, as well as their Windows versions 
(if available).
How do you make a final decision of what tools to use for testing (or how do 
you report this to the client), if they come up with different results on 
Black Box tests, like open ports, OS versions, etc.?