Agree totally with Guest. If you do record quiet noises though make sure you set your machine to the H setting and you get the volume level right.

Too high a level and it clips and sitorts and sounds awful but if you record at too low a level you can normalise the volume in Audacity or other package but you will also bring up all the background noise and can it sound equally grim.

It's worth doing a little test and checking that the levels are reasonable before you do a 'proper' recording