Mounting an HDD with windows installed, on a new PC?

It's not likely to work. You have drivers installed that to not apply to the different hardware. You also have hardware that does not have drivers installed for it. The mix of the two (or even one of them) will easily make Windows unbootable.

I've done this successfully a few times with XP but most of the time get the same result you did.

Nothing to lose, right? Try it with Win 7 and see what happens. The only concern I have is whether the copy of Windows 7 you are moving is an OEM versions. If so then it's tied to the original hardware so legally you are not allowed to do this. As an experiment though, it would be interesting to see what happens.

Cloning is the correct for seeing one installation on several machines provided you have a volume license. Businesses do that regular with hundreds with one master disk.

Simply moving a drive into a new machine with a different set of hardwares will obviously have the same negative effect regardless of which version since the installation and drivers installed are still tied to the first machine.

When simply going to change the brand of memory here on a new build MS got a call! That's with the 64bit 7.

You would first need to clean everything up as far as existing drivers since removing them ahead of time will also remove the registry entries pointing to them.

For long term use don't bother trying to see that pre-existing install activated unless that will become your main system to start with like an upgrade into newer hardwares. That's where a clean install would be what comes to mind right from the start.

For a quick look not a problem. I tossed a quick temp install on one case here lately to find out what would work and had some interesting results for the old boat anchor!

It works about half of the time I've tried here, swapping out all of the drivers in a cascade which requires several restarts. However it then runs fine and has never checked out less than perfect using chkdsk, sfc, or performance-wise.

There is a program Paragon Adaptive Restore that prepares the OS by removing all of the drivers first.

And if it won't start the first time, see if you can boot into Safe Mode and swap out your chipset and display driver which also often works.

Cleaning off all device drivers except for video and sound if the same drivers work for the video and sound being the same would be the first item. For other mismarches however you could easily end up seeing a blue screen or two until those are tended to.

Having removed all drivers however would be the best move from the start since this is a major change of everything. Your memory, hardware, and even bios configurations between two different systems will be the obstacle for the most part.

Do something to such that it boots it up, then do an upgrade install within the OS. This should replenish all your drivers. However, the booting up part is hard depending on the difference of your hardware. I, for one, never successfully booted a hard drive with Win 7 in it from an old system to practically anything.

The major factor should probably be your chipset, your motherboard, and your processor difference. The greater, the harder.