A 500MB /boot partition? Thats pretty big. I remember people complaining that Redhat/FC has a default of 100MB /boot partitions and people complained about that.

I used the default boot loader during the install process (Is grub the default boot loader?). I have two hard drives on this PC and I let D/lx use all of the space during the install. How do I fix ...

If you are unable to boot into Windows after installing Linux Mint or any other distro on your computer, try updating GRUB, using Boot Repair, and adjusting UEFI settings.