I am using Sony Vegas Pro 8. I am editing an HD project and rendering my project out as .mp4. I have noticed after rendering and watching the video that the audio is just slightly off... it was perfect when I was editing in Vegas. Is there any logical solution to this, or has anyone else noticed this?... or... Am I on crack? It is 4/20!

More details:

-I am working with 44.1kHz sample rate 16 bit audio. I know most video is done in 48kHz, which I'm not really sure why. I should probably research.
-My footage is shot with a HV30 at 30P
-I am also using Eugenia's export settings for Vimeo.com Her Settings

I'm not sure if any of these things could be playing a role in my problem, so that is why I listed them.

ALSO! I have noticed that just uploading to the web seems to knock the audio off a tad as well. I noticed this back when I would upload my standard defintion videos to Youtube. Any ideas on a fix on that too?