See http://support.microsoft.com/kb/950527 for the ConfigMgr 2007 hotfix that adds new supported platform entries for:

  • Windows Vista Service Pack 1 (SP1)
  • Windows Server 2008
  • Windows Server 2003 Service Pack 2 (SP2)
  • Windows XP Service Pack 3 (SP3)

These changes should be included in ConfigMgr SP1 too, so you can choose to wait for that too.

A separate hotfix for SMS 2003 SP3 should be available in the near future.