Don't do what I did or you will spend hours on the phone trying to get to the correct person.
I have an Acer 5315 that I upgraded from Home Basic first to Home Premium and then to Ultimate. That was my first mistake. I should have just gone from Basic to Ultimate.
OK, I really started to dislike Vista so I got a larger HD and installed XP and then I reinstalled Vista, in order to dual boot.
I did my upgrade purchases through the AnytimeUpgrade Marketplace (THAT WAS MY 2ND MISTAKE)
So, I figured a quick call and I should have it. Well, it has been about 1 week and I think I finally found the responsible party. They have agreed to send me a new disk (really don't need it but he said FREE) as well as the Product Keys for both of my upgrades. Sweet!
BTW, this notebook running XP with 2 GB of RAM flies! The same does not go for Vista. Lock-ups, applications hanging and a bunch of other things prompted me to install the XP. I needed to keep the Vista simply because I feel a responsibility to support any of my clients that went with Vista.
Following is a link about the Acer Hardware upgrade. I have a Core Duo T5450 in mine and it helps a lot. Just remember to upgrade your BIOS. http://forum.notebookreview.com/showthread.php?t=267688