Vocal distortion

Hi folks. A little help would be appreciated here.
I seem to be getting a vary compressed and distorted  sound on my vocals, yet the system sounds very clean through the headphones. I'm wondering if I have some setup issue with the windows 7. Any suggestions on what might be causing this if it is not the mic and pre?
- Jim

Check your device setup? Such as if you have it set for 24bit rate audio but your sound card is only good for 16bit. I know the dithering process can cause this issue. Other then that I'll second M_Glenn_M. 

I seem to be getting a vary compressed and distorted sound on my vocals

 
Sounds like clipping to me.  Check the gain?  What's your signal flow?  What soundcard are you using?
 

yet the system sounds very clean through the headphones.

 
What do you mean by this, exactly?  I'm sure someone here can help, with a little more info.  :)

Thanks.
I am running a Sterling condenser mic (under phantom) to an ART USB dual tube pre connected straight to the computer via USB. There is no sound card. Headphones are coming from the ART preamp (and that signal is clean).  One thing I noticed is that when I run the "microphone setup" on windows 7. the mic comes in blindingly hot, and the system corrects it down to 10 of 100 for gain. Still sounds bad with this correction.
Would a real sound card fix all this? I thought sound cards were about output.
If so, what do you recommend (keeping a tight budget in mind)?

OK.... a few things here...

The ART is your sound card.  It is much better than the soundcard in the computer so you always want to use the ART for INPUT and OUTPUT. 

Your mic also seems to be of decent quality. 

Lower the levels on the ART as low as is needed to keep the signal coming in very clean.

Also..... check to see if the ART has a software control panel. I know that my Saffire does. When I installed the drivers to my interface, it also loaded the software control panel for my interface. This software control panel is very very important and critical to the proper operation of my interface. It actually controls the input levels and the output levels that I am working with. I have the input level on the face of the SAffire to control levels from the mic, BUT, the levels going out of the saffire into my DAW and returning to the saffire outputs are set IN THE SOFTWARE control panel.  I had to take the time to adjust those levels in the interface's control panel. If they are set wrong, input to hot and output low, I can easily have a totally distorted output. The proper adjustment gives me a clean input and a clean output and I can control the levels in the proper range with my knobs on the interface.... normally set to 50% on the knobs. All the knobs do is let me stay out of the red and off the bottom. 

In post 7, you said you monitor with headphones plugged into the ART and they are clean.....BUT... you DID NOT state how you are monitoring the speakers.  Do you have monitors plugged into the ART? OR...are you using the computer factory soundcard to play back the music?  If you are monitoring using the second one...the factory soundcard.... that is very possibly the problem..... you really need to monitor from the ART outputs into some powered monitors. 

Be sure to use the ART as the only soundcard in the system. If you are monitoring from the ART with powered monitors, let us know that and then we can look at other possibilities as to where the distortin is coming from.