Windows 7: best way to reinstall windows 7 Ultimate

I upgraded from Premium to Ultimate several months ago and have been noticing along the way that it corrupted some of my operating system programs such as the Diagnostic Policy service and troubleshooting as well as media player 12. What is the best way to reinstall a clean version of Ultimate and save my programs and files?

thanks!

You are going to have to Backup your data whatever route you take

I would recommend an External HDD and to backup the files Manually (Copy and Paste)

After that you can follow this tutorial on how to do a clean Install with an Upgrade disk

Clean Install with a Upgrade Windows 7 Version

But the programs you have to reinstall. Your system shows the typical syndroms of an upgrade-install. A clean install should fix those.

You can't do a clean install "and" retain your already installed programs. You will have to re-install your programs after the windows clean install. You can backup your files such as documents, pictures, etc to external media before hand though. And then just copy them back to their respective folders after the re-install. Clean refers to wiping the drive clean before installing windows. You could copy the program folders to external media but each program makes entires into the windows registry when installed. Those entries will be lost when windows is re-installed and the programs won't work if you try to copy them back in to the program files folder. They will have to be installed again to work correctly.

Tips to get a perfect clean reinstall: Reinstalling Windows 7

I would clean the HD first.
SSD / HDD : Optimize for Windows Reinstallation