Transferring Fresh Install Win7 HDD to another machine?

For some reason, I cannot install Win7 onto this new gateway PC that I have, but am able to do it on my older PC. Both are capable of running 64 bit, both have new and working memory, hardware. Now I understand that when you do install windows for the first time, your hard drive "marries" your motherboard. Thus when I put the hard drive into the new machine after a fresh install, it gets stuck on "windows is starting" and refuses to boot (ClassPNP.SYS in safe mode). So is what I am trying to do possible? If so, how do I do it?

If you use a program like Acronis True Image with their Plus Pack add-on it allows you to do a Universal restore to unlike hardware.

There are other programs which do the same thing.

You will need a separate license to do this.

But I must say that if you can't do the install on that hardware then something is wrong with the hardware and moving the OS from one PC to the one you can't do the install on may not work.

In most cases when you move Win7 to new hardware it needs to have the drivers adjusted, SID/HID's removed to start.

You can achieve this by Sysprepping the install on the old hardware first: SysPrep to move HD to another computer

The same thing can be achieved booting Paragon Adaptive Restore CD on the new hardware, running PNP Adjust on the moved installation.

Or you can use Acronis Universal Restore as suggested which will make the adjustments during reimaging.

I cannot install Windows 7 onto this new gateway PC that I have

Why are you reinstall a new install?

Did you make the Gateway OEM manufacturer's Recovery Disks?

You can Order Acer recovery disks from here:
https://secure.tx.acer.com/RCDB/Main.aspx?brand=acer