How do I enable stereo mix? Help please!!

Are you referring to the "What You Hear" or "System Mixer" that is needed to record streaming audio?  If this is what you are referring to, the Dell integrated audio does not have the function on most systems (and other vendors such as HP do not either).

There is one possibility that SOME desktop system users have found that will work.  No guarantees but it's worth a try:

"Go into Control Panel's "Sound" then "Recording" Right hand click in a blank area and check "Show Disabled Devices" Then click properties and under Device Usage click "Use this device"

Umm that didn't work it just said what's this mean and I'm talking about like using it for people to hear the music i'm playing on vent and thanks a lot for responding :)

I'm confused on exactly what the problem is, now.  Your second post muddles it up more. 

Basically, do you have any PC audio at all? Can you hear anything? - system sounds - CD music, sounds in games?, etc.  Or is it that you can't hear anything?   Or is it your microphone is not working in Internet chat sites?

You know like you want them to hear the music you are playing you have to have stereo mix where you go in recording there should be a option of stereo mix I don't have that and i mean like yes I do have sound.

It sounds like you are calling the "System Mixer" (or "what you hear" function) as the "Stereo Mixer". 

If the procedure I gave you did not enable the "System Mixer" then yours is like most that do not have it.   It will not interfere with playing audio files that are on the PC (either a wav or MP3) and it won't interfere with audio CD's, audio in games, or even streaming audio from the internet.  The only thing you won't be able to do, without the system mixer, is the ability to record streaming audio from the Internet.

If you are having some other type of audio problem, other than the recording issue, it's not because of no system mixer.

If you are referring to a program to record audio on the PC, the free Audacity program will do that.  http://audacity.sourceforge.net/

There is a known issue with recording from the Line In or Microphone that you can record but you can't monitor what you are recording from the Line In or Microphone on the PC's speakers in Vista.  Dell has never updated Integrated Audio, in most systems, so that this function works.  Vista handles this function differently than Windows XP or other Operating Systems.  Why they haven't fixed the problem, I don't know but Dell has known about it since Vista came out. 

I have several "stereo mixers" in my music recording studio, but they have nothing to do with the PC.

Just went through a similar instance with wife's e510 which has the integrated SigmaTel sound.  Bought a good used Audigy 2 sound card and installed it in the e510.  Problem resolved.

The $30 (even at Wal-Mart) SoundBlaster Audigy SE will also do the job and provide the "what you hear" function so you can record streaming audio.  I've recommended it to quite a few on the old forum and reports back were positive on the inexpensive Audigy SE.

I have one of the Audigy SE's installed in my E510 with Vista Home Premium.

As this is a Laptop, best to repost in the Laptop section of the forum.  This section is for Desktops.  Someone in the Laptop section may have a workaround for this model. 

I installed a more recent driver located on the Dell site, and voila, Stereo Mix appeared as an option.