A mic question

[eXLuSiVe]

Is there any way I can make my mic record the sounds from my speakers?

What I mean is if I use my mic and put it close to my speakers while I play some music or whatever, I cannot send it to my friends through MSN with F2 because it says it didnt record any sound..
Do I need a new mic? Currently I've only tried with the xbox 360 headset because my other one broke because of my cat
I recall being able to use a radio and send sounds through the mic, but now I am confused and I really would like to be able to send some funny stuff through MSN.

Any help is appreciated