Simplest is an SM57 > xlr cable > usb or firewire interface (basically an external soundcard which connects via usb or firewire) into some free recording software, I use Reaper. For the interface there are so many to choose from that its hard to pick one, but my Presonus Inspire seems to be ok so far thoug has a few problems with the Vista drivers I think. I might sell it on and get an Edirol, the UA-25 and UA-25EX are interesting me.