Depends what OS you are using. If you are using 3.1 or below you can use a HD up to 4GB no problems. 4GB and up will need a patched device driver and tools that can handle the larger drive. OS 3.9 will be able to handle almost and 2.5" HD. I would get a 20GB or 40GB to be safe. The problem you will have is getting it partitioned and setup properly. With some of the newer larger drives you will need to boot from a WB 3.9 disk to get it setup properly. If you use a 3.1 disk it may not see it correctly. You can also try HDInstTools from Aminet, that tool seems to work great as well. Do not use HDToolBox from 3.1 or 3.0.
