Hi Flappo,
Ativan is a little stronger mg/mg then
diazepam and has a shorter half life, the effects are very similar.
A word of advise, don't take it to get high on, and never take more then you're prescribed, if you take extra you will always need more, tolerance works faster with benzo's then any other drug that I'm aware of.
This site is great for benzo equivalence info.
http://www.benzo.org.uk/bzequiv.htm