Right now I have a 2TB cache drive, but I never use more than a couple hundred megs, so I'd like to put a 750GB in as the cache, and put the 2TB in the array.

 

I've precleared the 750GB, but not sure where to go next..

 

I have stuff on the cache drive (sabnzbd and the like) that I want to bring over to the new drive; how would I go about mounting the 750GB drive, copying the info, and then assigning the 750GB to the cache drive slot?

This should work: Install and assign the new disk as cache. Follow the instruction in the following link, but skip the first step and replace ntfs with reiserfs: http://lime-technology.com/wiki/index.php/Copy_files_from_a_NTFS_drive

Thanks, that seems to be working well... Copying copying copying now!