If you run "yum update" on a CentOS 5.0/K12LTSP EL5 box, you'll be in for quite a download. You can read up on the changes here: http://wiki.centos.org/Manuals/ReleaseNotes/CentOS5.1/ I'll get to work on building ISOs for those who do a fresh install & don't want to have to download that many packages afterwards ;-) -Eric