Surprised there are so many pages for this - this topic has been beaten to death
Between a fat out of shape guy and a man who is fit, of course women will prefer the in shape guy. Being muscular by itself isn't a magic bullet though.
Getting in shape is only one part of the pie. The other things, career ambition, how good you are with people etc are just as important. If you are on this site this should be straight forward and you should be looking to improve the ENTIRE package, not just one aspect.
For many guys, the woman being nice looking is enough, but that isn't necessarily the case with most women (yes there will be times you'll succeed simply just because you look good - that's what spring break etc is all about).