Thank you. You are right.
I build this query, based on lastchanged is null, and it seems to work quite well.
Select Top 1000000 tblAssets.AssetID,
tblAssets.AssetName,
tsysAssetTypes.AssetTypename,
tsysAssetTypes.AssetTypeIcon10 As icon,
tblAssets.IPAddress,
tblAssets.Lastseen,
tblAssets.Lasttried,
tblQuickFixEngineering.InstalledOn,
tblQuickFixEngineering.Lastchanged,
tblAssets.Domain,
tblAssets.Userdomain,
tblAssets.Username
From tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
Left Join tblQuickFixEngineering On tblAssets.AssetID =
tblQuickFixEngineering.AssetID
Where tsysAssetTypes.AssetTypename Like 'Windows%' And tblAssets.Lastseen >=
GetDate() - 60 And tblQuickFixEngineering.Lastchanged Is Null And
tblAssetCustom.State = 1