i need to upgrade a disk

[Jonathan Horne]

i have a system that is FreeBSD 6.2-PRERELEASE, that i need to upgrade its 
single disk.  id like to keep all its existing slices the same size, and then 
use the unused space to create a new /opt slice.  would dd be the way to go?  
if so, could someone advise on its proper usage for duplicating one disk to 
another?

or, if there is an alternative way to skin this cat, im willing to learn 
whatever way might be the best.

cheers,
jonathan