Should I reformat?

[Mark Swanson]

I just bought OSX 1.3, downloaded the 1.3.2 update, and ccc'd my drive 
to a external firewire drive.  When I boot from the firewire drive, 
everything looks exactly like booting from the internal drive.  I've 
tested applications; safari, mail, word etc. and everything works.  My 
question is can I reformat the internal drive or is OS X creating the 
illusion that the external drive looks and acts like the original 
internal.  I know this might sound a little silly, but I don't want to 
reformat the drive and find out the external drive only looked like it 
was running things.  The external drive is at the top of the drive list 
and window but I can't eject the main drive "because it is in use"  
This makes me worry that it is still contributing to what I'm seeing 
and how its acting.  I don't want to loose what I have on my original 
drive.