Upgrading from XP to Vista receiving error

Hello,

Can someone please help me. I am having mad issues with a new computer I bought from Dell. They have sent an exchange and it has the same issues. It came loaded with XP and everytime you go into Internet or word documents, command boxes popup as you are typing and you haven't commanded it. So I thought if I upgraded to Vista that maybe this could solve the problem. Now that Vista is loaded, the sound button has a red x over it. It says No audio output device detected. Can someone please help me!! I only purchased this computer 3 months ago and it was the worst decision I could have ever made. I have had service techs out to change out several items including the harddrive, and keyboard and it has been sent back to dell.

Does any one know how to correct this sound issue or any of the above listed. I appreciate the help. Please not I am no computer wiz, so a step-by step process would be great.

Thanks