Does your MBO support MBR only, or both MBR and UEFI, or only UEFI?
If it only supports MBR, then that's what you have to use. But if UEFI, that would be preferable.
So the first step would be to define which sort of installation you can create, and which you want - MBR/legacy BIOS or the newer UEFI/GPT disk format.
Can't determine if the MBO supports UEFI, looked through the original purchase info from 2011 and don't see any references for it. Not sure if I can use a Linux command to see if it does. I read your GPT link and yeah, I'd much prefer UEFI/GPT disk format.
For interest: GPT vs MBR - and the advantages of GPT:
What’s the Difference Between GPT and MBR When Partitioning a Drive?
I'm unsure what you mean about a Win 10 DVD. Is this one you've created from an iso you've downloaded? Do you have one or are you just recalling Win 7 days?
Clarification: I bought a new, OEM Windows 10 DVD with product key in sealed envelope. It shows "1809" for the build. I did this rather than doing the download, ISO, and other things plus also wanted a DVD source media if I have to use it again. When I tried to install it, it looked exactly like Shawn Brink's installation guide. As mentioned, I got stopped at the "choose unallocated partition" and then the MBR roadblocks.
Now, if you want to download build 1809 (rather than 1903, the latest) you could use e.g. Heido iso downloader (search for it). And you could create a bootable flash drive.
Build 1809 is on the DVD, I've read a lot about upgrading from 1809 to 1903 but like to avoid jumping onto the bleeding edge too soon.
If you choose to use build 1903, it's much easier - Microsoft Media Creation tool (just search for it). You can create a bootable flash drive using that on another PC (same 'bitness' and base language).
I think I can upgrade to 1903 without the MCT as Win10 includes the upgrade tool?
Note that you do have the option of formatting the disk as part of the installation procedure.
Will the installation routine from the DVD include permission to delete the entire drive through the formatting choice?
- as you have noted, all existing OS-related partitions must be deleted, and the OS installed to unallocated space. (You can choose to retain data partitions you have created yourself).