I bought a Compaq PC about a year ago, preinstalled with Windows Vista. I then bought an upgrade disc through HP to get a full working version of Windows 7.
Fast forward to now and I've built myself a new system based around a Phenom II 1055T. I've got a Gigabyte 890GPA UD3H, Rev 2.0 (BIOS v. FDd) motherboard and the 95W TDP version of the 1055T.
I've transferred over my old hard drive from the prebought Compaq computer and Windows refuses to boot. I get an error, Windows offers to fix the problem, then tells me that it can't be fixed automatically and reboots. Repeats as many times as you like.
Ubuntu is absolutely fine though and runs great from the same disc, so as far as I can tell - it's not a disc issue.
I've got no reason to suspect that the Windows installation is corrupt, I can still access it from the other computer.
Yah, basically the OS likes to sink its claws into what hardware you used in the old build and doesn't want to let go. Unfortunately you will probably have to get a new HDD, but if you call/contact Windows they will let you use the same software and key.
edit: actually another option (if you don't need the data on the old HDD) is to just wipe it and reinstall using the new computer.
I was worried that's what the problem was.
I would just reinstall, but I have no installation disc and, if I can do it legally (which I'm not 100% clear on yet), I'd rather not have to buy another license for Windows 7.
I've contacted the Microsoft Q&A forums, hopefully they'll clear the matter up.