Used gpparted to create a partition on the disk, used clonezilla to backup an image to that partition. Its not NTFS so windows doesn't see it. I also have a separate partition for Data and that's where my Computer points to.

Another comment on one of the initial points, AVG used to store all the .bin updates that it downloaded until it clogged the disk, and I think AVast does this too, so find their stores and blow them away as part of your cleanup.