I recently purchased an Acer M5640 Desktop computer from Overstock.com being sold by Best Buy Outlet. The Computer came with no restore, no OS but did have the Vista OemAct Product Key on the side of the machine. This was not a surprise because it was listed as such in the auction. I attempted to install Vista using my own oem Home Premium disk and use the acer oemact product key but it said the product key was invalid. I then used a regular vista oem product key (found on the internet) thinking I could change the key to the legal acer oemact key once the install was complete. However, It still came back as invalid when I tried to change it. I called microsoft and of course they said I had to call acer. Acer said I had to buy their $40 recovery disk. About this same time, someone brought a computer in for motherboard replacement and so I sold them the Acer m5640 motherboard which is an NVIDIA GeForce7100 and 630i chipset motherboard. The person had XP on their hard drive so now I still have the rest of the Acer Computer with the vista product key (less motherboard). I purchased an ECS GF7100PVT-M3 NVIDIA GeForce7100 and 630i chipset motherboard which appears to be the same one used in the acer but I still can't get the Acer Vista OemAct Product Key to work and I don't understand why. I had an Acer Acpire laptop com in for repair and used it's default recovery DVDs and installed it's vista on the acer m5640 (now with generic motherboard) but still the Acer oemact vista key said invalid. I called acer again they referred me to microsoft who after some rangling gave me new product key that still says invalid when I try to type it in. I am baffled because I took the product key number from the bottom of the acer laptop that I had borrowed the recovery disk from to install vista on the acer m5640 and that key worked on the acer m5640. My question is how can I get my legit, valid product key on the side of the M5640 or the replacement key given to me by microsoft to be accepted when I type it in. I am sorry this post was so long but I wanted to explain the things I have tried so far. I know I could give up or use a cracked key but this kind of stuff is interesting to me and I'm sure I will encounter similar stuff in the future.