Before doing any update you should back up the Notification ("CMS") server and all databases.
KB45825 (http://www.symantec.com/docs/TECH41534) can be uninstalled from Windows Swerver 2003 Add/Remove programs provided the Recovery Solution AUP is current - it can't be uninstalled from Windows Server 2000.
KB45826 (http://www.symantec.com/docs/TECH41535) can be uninstalled by browsing to the msi, right-clciking and selecting uninstall: C:\Program Files\Altiris\Altiris\Notification Server\NSCap\Bin\Win32\X86\Recovery Server Package\AeXRSServer.msi
Back up GetDelBlobRecs.sql, Reports_ServerJobHistory.sql and Reports_GetMetaJobInfo.sql also as the original versions aren't uninstalled when the msi is uninstalled.