Can't Record Anything with AvRack! How to capture audio streams?

hi everyone. i used to use AvRack to record anything playing on my computer. but recently i just bought a dell inspiron laptop and installed the AvRack program, but when i press record it doesnt record anything!

i think the problem lies in the "Volume Control".
when i used to click the Windows Volum icon, i used to get the "Stereo Mix" volum bar, but in this new laptop it is absent. the volume control only has "Volume Control", "Wave", "SW Synth", and "CD Player" volume bars.
does anyone know how i can change it so that i have the "Stereo Mix" option. i really need to record something before it is taken off a website.
cheers for any help.

Hanif