It depends on what you use. I have used a bunch of different things but probably the most basic is a roxio/itunes combo descirbed here: http://urlgreyhot.com/personal/node/849 . My question to you is: why do you want to do this? I will say that unless you:
a) have a tiny collection of vinyl that you want to rip
b) are a DJ and are tired of spending your afternoons at the gym
or
c) are seriously going to sell your entire collection
you are going to be much better off just breakin out your turntable when you want to listen to your vinyl. For any significant number of albums you are looking at a huge commitment of time and energy. And finally converting vinyl to mp3 isnt about great quality, its about acceptable quality while gaining digital flexibility without having to re-buy the tunes.
I have a small amount...maybe 5 that I want on my iPod/iMac. Certainly not enough to warrant buying software to do so. I know I can use Audacity, but was wondering if Garage Band would cut it.