If you cannot use your DVD drive you should read this two articles on Microsoft wich covers this problem in depth. You will need to make some registry changes to solve the problem.

The CD drive or the DVD drive does not work as expected on a computer that you upgraded to Windows Vista ( Read it )

You can no longer access the CD drive or the DVD drive, or you receive an error message after you remove a CD recording program or a DVD recording program in Windows XP ( Read it )