A little guidance goes a long way.

I intend using the mic jack on a laptop running win7 & vb2010

I have the following application requirements. I need to detect if there is sound coming from a mic, and if so, record to a wav file for 20 seconds, then close and save the wave file, wait for new sound and do it again. The mic will be switched on and off so that background noise doesn't mistakenly trigger a bogus recording.

I really am not sure of the best place to start researching this....any guidance is greatly appreciated.