how install win w/o wiping the disk

[compdoc]

> But it's this GPT bit I am confused about.  Where did it come from?
> Ubuntu?  Chrome OS?  If the latter I can wipe that off my disk.

GPT is required for drives larger than 2.19 TB in size. And your motherboard
requires an UEFI capable bios in order to boot from a GPT partition.

If the drive is smaller than that, use Gparted to change the partition type.
I don't know if it's possible to change and keep your data. 

You should proceed as if it will not, and backup your data.