Someone gave me an old laptop they bought at an auto junkyard for $1US. The computer didn't work so I pulled the hard drive and extracted product keys from it. I got keys for Windows 7 Home Premium and Office 7 Standard. Checking the specs showed the computer originally came with Windows Vista. Using Microsoft PID Checker indicates that the Windows 7 key is Retail.

I used this Windows 7 product key to activate Windows 7 on a desktop computer I have. There was no problem doing this because I was using a Retail key which allows it to be transferred on another computer.

I haven't read all the posts on this thread but is your Windows key Retail or OEM? Also, have you tried calling Microsoft for assistance with activating Windows?

BTW, earlier this year I installed Windows XP on an old computer. Phone activation was unsuccessful so I called Microsoft. I was surprised that Microsoft was very patient and helped me activate Windows XP. Note I had the original CDs and Product Keys for two copies of Windows XP Pro.