Size limitations:
It's depends on the controller. Mine is a custom hungarian autoboot ide controllrel with 4 ram slot. When i bought it ages ago, it was a miracle for me. At that time of course i use it only with 100-200MB hdds.
But checked last year it could handle a 80 GB (yes gigabyte) samsung hdd without problem. (but can't see most of the 2-3 gb hdd's.)