is this what you need ?
Select Top 1000000 tblAssets.AssetID,
tblAssets.AssetUnique,
tblAssets.Domain,
tblAssets.Description,
tblOperatingsystem.Caption,
tblOperatingsystem.Version
From tblComputersystem
Inner Join tblAssets On tblComputersystem.AssetID = tblAssets.AssetID
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysOS On tblAssets.OScode = tsysOS.OScode
Inner Join tblOperatingsystem
On tblAssets.AssetID = tblOperatingsystem.AssetID
Where tblComputersystem.Domainrole > 1 And tblAssetCustom.State = 1
Order By tblAssets.AssetName