Windows 7: How to "record what you hear"

I'm trying to do two things
1) make Audacity record what plays through my speakers, like a midi for example
2) make my computer play sound files as it it was a microphone, to, for example, play music over a skype call.

I have realtec audio drivers/card/thing, and under XP all I would have to do is mute/unmute stereo mix. When it was muted, sound didn't play like a microphone, and unmuted, my output acted like a mic..

However, now, I can't figure out how to do that. When I run audacity under XP compatibility, it lists stereo mix as an imput device but it doesn't record anything. Also, the realtec program that is listed under control panel isn't the same; there is no mixer panel that lets me control stereo mix..

You might have to experiment to find which fix will work for you, but something in here ought to do it:

Record "what you hear"