[CentOS] performing binary upgrade centos 4 to 5

Sun May 6 23:54:26 UTC 2007
Dave <dmehler26 at woh.rr.com>

Hello,
    I'm trying to take a box from 4.4 to 5.0 and doing it via binary yum 
upgrade. I'm following the procedure at:

http://lists.centos.org/pipermail/centos-announce/2007-April/013660.html

for taking a 4.x box to 5. I've removed any unneeded rpms, and confirmed the 
state of the system. I downloaded and installed centos-notes-5 and ran an 
rpm -Uvh centos-release-5 which worked. I imported the centos 5 gpg key and 
confirmed the status of my yum. Then i ran:

yum upgade

this didn't work, yum didn't recognize that as a valid option. Is that a 
mistype? Or is there another step i have to do?
Thanks.
Dave.