You don't make any mistake.
The first time you connect your drive, Finder see it like a hard disk and more this is an empty disk, there's no file in it.
When you eject or leave your session, Finder writes in it some file to remember on next opening which look you have choosen and some useful files for himself that identify completly the disk and which driver must be used.
So the second time, Finder will use a firewire drive with the icon of a firewire drive.
Hope this helps, see you later.<br /><br />Mac is for my pleasure, iPod for my ears.<br />If you want I can write french.<br />P.S : Apologize my bad english writing.