How do you know that it is supposed to write DVDs? Do you have specs on the CD/DVD that say it is a DVD-RW and not a DVD-ROM? Have you used it to burn DVDs before, either in the current machine or some other machine?
Do you have another PC you can install the DVD writer in to make sure it is working? DVDs use the standard ATAPI drivers, and don't need drivers for a specific machine or operating system.