MERGE dbo.tblInstances AS TARGET
USING dbo.tblInstanceImport AS Source
ON (Target.InstanceName = Source.InstanceName)
WHEN MATCHED THEN
UPDATE
   SET Target.[Home] = Source.[Home]
      ,Target.[Version] = Source.[Version]
      ,Target.[DateCollected] = GetDate()
WHEN NOT MATCHED BY TARGET THEN
INSERT  (tblNewInstance.[Name]
        ,tblNewInstance.[InstanceName]
        ,tblNewInstance.[DateCollected]
)
VALUES  (Source.Name
        ,Source.Instance
        ,GETDATE()
);