Sort of off topic, but the 5.25" disks made me remember this since I have an IBM PS/1 with both 3.5" and 5.25" high density drives...

If you use DOS, your disks will always be formatted to the highest capacity your drive is capable of (unless you use a really old version of DOS that doesn't recognize larger capacities). In other words, if you type format b: to format your 360K 5.25" disk, it will format it as a 1.2MB.

Yet another problem Macs of that vintage don't have...