Yesterday, I found this excellent modified version of Windows 7 which is compatiable with modern PC's and have tested it with my MSI laptop for dualbooting with 10 and it works well with the UEFI and CSM option turned on at the BIOS.
I now have Windows 7 running on my hard drive and Windows 10 running on my SSD. It also comes with most tools that you need like Winrar, 7zip and has Google Chrome and Firefox and comes with it's own theme! The edition that is modified is Windows 7 Ultimate with SP1.
Here's a link to the Windows 7 Bluecore edition:
http://www.teamos-hkrg.com/index.php?threads/windows-7-blue-core-64bit-axeswy-tomecar.9053/