Good morning, jpmurphy.
Formatting the C:\ drive, even though you're not using the Windows installation thereon, would be a bad thing to do. Windows sticks a bunch of very neccessary files on the first partition of a hard disk that are used to load Windows. The easiest way to free up all that extra space would be to manually delete the folders on the C:\ drive, leaving these critical files intact.
You can safely delete all of the folders, including the WINDOWS folder and Program Files folder without damaging these files as they are stored in the root of the partition (C:\).
After deleting the folders you don't need, click the Start button and then click Run. Type msconfig
in the box and then click OK. This will launch the MS Configuration utility program.
Click on the BOOT.INI
tab (see picture) and then click on the Check All Boot Paths
It should detect that something's wrong with the C:\ Windows installation (it's gone!) and ask you if you want to remove its entry. Click Yes:
Ket us know how it goes!