I believe that is one of the differences between OnePass and WorldPerks. You can upgrade for free on NW on award tickets, but not on CO... (see the 'elite' section on CO's web site, it specifically states on PAID fares only)
http://www.onepass.com/elite.htm
Still, not good enough for me to switch from primarily using CO OnePass to primarily using NW WorldPerks...
(I wonder if this will change when/if 'Wings' ever takes flight)
[This message has been edited by steve100 (edited 01-12-2000).]