If you are running a 2.4.5 install you will notice that there are still a few bugs (most of which have been patched at this point).
The patches that I recommend for any 2.4.5 Zenoss users are the following.
Patch 15003 - Corrects the following bug: http://dev.zenoss.org/trac/ticket/5494
Patch 14397 - Adds the following feature: http://dev.zenoss.org/trac/ticket/5375
Patch 15214 - Corrects the following bug: http://dev.zenoss.org/trac/ticket/5473
(this patch only partially corrects the issue, read the comments on the Trac page for details)
Patch 14049 - Adds support for the use of "dmd" in transforms (as you would use it in zendmd).
Patch 13304 - Corrects the following bug: http://dev.zenoss.com/trac/ticket/4914
Patch 16733 - Corrects the following bug: http://dev.zenoss.org/trac/ticket/5978
These patches can be applied with the following command (run as the zenoss user):
zenpatch 15003 && zenpatch 14397 && zenpatch 15214 && zenpatch 14049 && zenpatch 13304 && zenpatch 16733
Restart Zenoss after applying the patches.
Also, if you are using the WMI Data Source ZenPack you will want to install version 1.5 of the ZenPack before upgrading: http://community.zenoss.org/docs/DOC-3392. If you upgrade to Zenoss 2.5 without upgrading to version 1.5 of the WMI Data Source ZenPack you will break your Zenoss install.