No "Stereo Mix or Mix"

[ToRoKoKiLL]

Ok, this is straight from the shoutcast readme:
For VOICEOVERS, CROSSFADING, or non-PCM INPUT material, you will need to set the recording mixer to record from the soundcard's playback channel. This is usually one of the rightmost options in the recording mixer, and can be labeled things like Stereo Mix or Mix
Now, I want to both play stuff comming from the PC and the Mic. There is no "Stereo Mix or Mix" option in my Recording panel. How can I get around this problem? (BTW, I'm using XP)
Thanks in advance!