There was a bit of controversy in Symantec Monitor Solution 7.6 documentation regarding Windows 2003 support. It is stated in DOC8053, page 15 that among the default packs there is a pack for Windows 2003, that allows "to monitor the health and performance on the Windows 2003 servers including disk, memory, network, and processor".
However DOC7720, page 59 states that the installation of Monitor plug-in is not possible on Windows 2003 machines. The plug-in requires Microsoft .NET Framework installation, but Windows 2003 does not support it.
Windows Event Viewer
Error 1904 Module C:\Program Files\Altiris\Altiris Agent\Agents\monitor agent\AexStateMachine.dll failed to register. HResult - 214024769
The controversy was generally caused by the approaching Windows 2003 end-of-life. A point-fix has been introduced for Monitor Solution 7.6 HF1, i.e. you need to have HF1 installed before installing the point-fix. Microsoft will end Windows 2003 support in July, http://www.microsoft.com/en-us/server-cloud/products/windows-server-2003/, and therefore the fix will not be incorporated into future ITMS releases.
Please contact Symantec Technical Support in order to obtain the fix.