Capture audio to/from headset on Windows PC

We want to develop a call recording process that works on a Windows desktop and does not depend on the specific telephone application used by the PC. So this would result in recordings regardless of whether the calls were on Skype, a VOIP softphone, Google Voice or some other softphone client. Our idea is to tap the audio going to the speakers/headphones and coming from the microphone. So the software would need to do the following; 1) Identify the drivers in use (or at least be able to work regardless of the drivers in use) 2) Monitor for the presence of audio going in/out of the headphones/speakers/microphone 3) either record the audio directly (as in create an audio file) or packetize the audio in a standard codec (such as g.711) 4) Store or send the recordings or packets to our program for processing 5) Have a software interface that let's us start/stop the process to designate when a call starts/stops The requirements above are all pretty conceptual, so you would need to suggest an approach to doing this. In your bid you will need to tell us the following: 1) Generally how you will capture the audio without interfering with the user's use of the phone. They need to be able to hear and speak normally. 2) Whether you would create a recording or create packets for use to process and turn into recordings 3) What format to expect the audio in