My suggestion is that on Atari your C: partition must always be a TOS one. Even if you can boot from other partitions it saves you from a lot of trouble. Personally I have quite a few TOS partitions all at 1GB (system, office and dev, games, demos) and 2 MiNT partitions (ext2 2GB and F32 34 GB that I was hoping to be able to mount under windows but that idea failed). EXT2 and F32 partitions can be of any size.