Breaking down the SQL 2008 support for ConfigMgr 2007
Upgrading ConfigMgr 2007 RTM
Upgrading to SQL 2008 for ConfigMgr 2007 RTM version is now supported by Microsoft, but a clean installation is not. BEFORE the upgrade you must first apply the following Hotfix: 955229
Installing or Upgrading ConfigMgr 2007 SP1
A clean installation (and upgrade) of SQL 2008 onto a ConfigMgr 2007 SP1 box is supported, BUT you must first apply the following Hotfix: 955262