It really depends on what kind of riding you plan on doing and on what kind of terrain, as well as your physiology in terms of fit. Take a look at Dave Mann's explanation of frame geometries to get some ideas as what "style" of frame would work for your purposes: http://home.comcast.net/~pinnah/dirt...-function.html. Whether or not you want a frame made of Reynolds 531 isn't your best starting point!

Neal