You can only use IDE harddrives because you don't have any scsi interface on your A1200, right?
Else the choice is up to you.
The cable is smaller because A1200/A600 is designed to use 2,5" harddrives and not 3,5" harddrives that is in the most ordinare pc computers.
And the cable you have has 44 pins and the bigger IDE cables only have 40 pins and thats because the extra 4 pins is for power that is separate plugged in on ordinary 3,5" harddrives.
2,5" Harddrives is commonly used in pc notebooks or laptops.
You can use ordinary 3,5" harddrives but you need to buy a 2,5" -> 3,5" converter.
But you need to solder on a 4 pins power cable that is suppos to be connected to the harddrive.
4 Gig is the max HDD limit if you don't buy OS3.9, have a different filesystem or buy a ide upgrade ie IDEFix or ATA2 controller.
