ok, i might as well chime in on the bullet gun thing too.

they both hit the ground at the same time. gravity affects them equally, but the one fired from the gun also has a forward motion component to it. i could get into vectors and all the scientific crap but i wont.

edit: here is a link explaining lift. note the final paragraph titled 'no motion, no lift'.

http://www.grc.nasa.gov/WWW/K-12/airplane/lift1.html