I use Gallery 2 for the Aldershot & Farnham CC website members gallery.
The actual website (
www.afccweb.net) is hosted by 1 and 1. The members 
gallery is hosted by me at home on
Wait for it...
An old type (PPC) Mac Mini running Fedora 9.
As has been said, if you satisfy the prereqs, create a mysql db and then 
the installer takes you through the whole installation process.
If you goto 
www.afccweb.net, select Members gallery and choose a member 
( No me as I'm in the middle of reorganisizing my gallery) you can see 
the sort of customisations that a relative beginner to gallery  can 
achieve in 4-5 hours of fiddling.
Stephen Davies