WSS 3.0 April CU package
MOSS 2007 April CU package
Start from April Cumulative Update, the packages will no longer install on a farm without a service pack installed. You must have installed either Service Pack 1 (SP1) or SP2 prior to the installation of the cumulative updates.
After applying the preceding updates, run the SharePoint Products and Technologies Configuration Wizard or “psconfig –cmd upgrade –inplace b2b -wait” in command line. This needs to be done on every server in the farm with SharePoint installed.
The version of content databases should be 22.214.171.12404 after successfully applying these updates.