Installation issue from upgrade to Original OEM problem _MB?

I have an MSI MB with a video issue and want to switch to another board, an Asus. My W7homePro64bit is an upgrade going all the way back to WinME! This is the first time I've tried to change a major component with W7 and when I put the drive and components onto the new MB nothing happens. Everything was properly installed. The drive would boot, but never loaded the OS. When I put in the W7 disk to repair/install, it says my serial number is not valid for the install. I reformatted a drive and tried to install, but it would not even ask for the original earlier edition for a valid serial number, it only wants an original serial number.
So I purchased an OEM disk, full install.
So here's my issue - I have years of programs and files and such all organized the way I like into a 600GB+ C: drive. I do not want to reinstall everything one by one, I want to simply replace the MB, but I cannot figure out how to do that even with a serial number for an OEM, how can I transfer my current system to a new build on a new MB?
Thank you for your thoughts.

You can't expect Win7 to start on new hardware without adjusting it. The way this is done is to SysPrep to move HD to another computer before you change the hardware, or if it's too late boot Paragon Adaptive Restore CD on the new hardware to P2P Adjust the OS to boot on the new hardware.

This process removes Hardware ID, Security ID, activation and drivers, so you'll need to be patient and monitor all of the drivers reinstalling when it does start from the animation in the System Tray, making several requested reboots. Then enable Automatically deliver drivers via Windows Update (Step 3) to run all rounds of Important and Optional WIndows Updates until there are no more. There will be a many patches for the new system and more drivers.

You probably already know you cannot use the old OEM license on a new mobo as the key becomes tied to the mobo and dies with it. To activate you'll need to buy a new key for your version. You can use Upgrade version, if necessary doing the workaround in Option 3 of Clean Install with a Upgrade Windows 7 Version if it rejects Upgrade key - it doesnt' matter because you qualify so it will get activated even if the old OS is not installed then or now.

This is all assuming you have a perfectly running install which seems unusual if it was upgraded that many times. Have you ever even enjoyed the perfect performance that comes with a perfect install as compiled in Clean Reinstall - Factory OEM Windows 7? Those steps are same for retail OEM, and will assure you get and keep a perfect install.

If you have any questions, ask back.

I had quite some difficulty trying to log back in - why they ask for a name was beyond me, i never wrote it down, i thought emails would work -= anyway thank you is what I wanted to say.
Sorry it took so long.
Your solution was depressing; so I have to decide which is more work, porting the old or rebuilding it one piece at a time. Thank you so much for the excellent references and resources, I will be going over them for some time.
Be well and be safe.

This is an interactive forums. You ask questions and we provide possible solutions, which you try and then post back results for more suggestions.

In this case I gave you the workaround to achieve what you want to do, even though with that many Upgrades is is likely the only way you will experience true native Win7 performance is by doing the Clean Reinstall - Factory OEM Windows 7.

However you can try both.

Let us know how it goes.