Generally you want about 1-3" of standover clearance to the top tube on a road bike, and 3-6" clearance on an MTB or compact road frame (ie with a sloping top tube). Given that clearance, the more critical dimension is the length of the bike from saddle to bars. This varies between different designs and manufacturers.
Find a good bike shop who can advise you.
For more detailled info on fit, check out
www.peterwhitecycles.com/fitting.htm
http://www.sheldonbrown.com/frame-sizing.html