This is one of those things where you can spend a LOT of money buying gear, or, you can pop for just a few hundred, it depends on how you want your recordings to sound, how professional you want to be, and how much you want to play with these items.
For now, your laptop and mic seems not enough. Why not try two mics (Shure can be relied upon) and a small mixer, 4-8 channels, available from $30-$200 and up at Musician's Friend: http://www.musiciansfriend.com/navigation?q=mixer&st=
. For the more inexpensive mixers check out the Tapcos, Mackies, Behringers, and of course the well-made Peavy (I prefer the Peavey, and not just because it's made in the USA). You won't need a powered mixer if you're just recording unless you plan to use the system for playback (like a PA system).
Spreading the two mics apart will give you better coverage, and a freeware audio recording and mixing studio called Kristal is available on the net. Of course you'll need a couple of mic stands, or something on which to hang the mics, and all the proper cables.
This is a low bucks (but decent quality) intro to the world of audio recording. From here the sky's the limit.