This chart shows speed of action and comparison of effects for benzos:

http://www.medscape.com/content/2003/00/45...456734_tab.html

Check out the above, looks very helpful for us anxiety ridden folks.

Chimpmaster provides this link which shows approximate benzo equivalent dosages:

http://www.benzo.org.uk/bzequiv.htm

And this source from Dr. Bob's is provided by doc's and has source references. [added 7/2007, a.m.] Thanks Penny!
http://www.dr-bob.org/tips/bzd.html