If it were an activation problem the Vista installer would still launch but then spit out an error after you enter the product key or down the road after installation. Thus, the problem lies elsewhere.
My questions to you are:
1.) If you are inserting the DVD while running Windows, have you tried right-clicking the DVD drive and selecting Explore?
2.) Have you tried booting to the DVD instead of running it within Windows? (Required if you want a clean installation.)
3.) Is it just the Vista DVD or others as well? Are you sure it's a DVD drive and not just a CD-ROM?
Let us know.
I recently purchased Vista Home Premium and when i put the dvd in the drive it cames making a huming sound and stalls the pc and i cannot access the drive, does this mean its been activated or is there another fault?