Matt mentions an important point; having too many drives connected will slow your computer to a crawl. How would I know that? lol
I would be interested in hearing that story. I am not aware that having many drives plugged in would have any affect on the computer's performance.
When I said not to keep too many drives connected, it had nothing to do with performance. I was talking about data security. I meant that you should not have all your drives connected because the same lightning strike or virus can take them all out. In other words, make your backup, then remove the drive from the computer, and store it physically somewhere else.