Should I reformat?

[Mark Swanson]

I just bought OSX 2.3, 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/ desktop 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.