Just one point to add to Bengt's..
If you're only
cutting between shots, you can use iMovie. But if you want to add
transitions (..fades, dissolves, etc..) then you'll probably have great difficulty keeping everything lined up with the audio, because iMovie "eats into" the tail and start of movie clips when they're laid over one another to apply transitions (..except for the 'Overlap' transition). This will throw your timing completely, unless you make each clip -l-o-n-g-e-r- by the duration of transition you want to use ..i.e; you'll need to make a clip two seconds longer, if you want to apply a 2-sec transition, and still keep it in sync with the separate audio track!
So cutting's OK. Anything fancier, do as Bengt says!