I apologize for not understanding your query logic. I thought I was correctly interpreting your suggestion and updating the query. Below is the full code of the query.
Select Top 1000000 tblAssets.AssetID,
tblAssets.Domain,
tblAssets.AssetName,
tblSoftwareUni.softwareName,
tblSoftware.softwareVersion,
tblSoftware.Installdate,
tblAssets.Lastseen,
tblAssets.Username,
tblAssets.IPAddress
From tblAssets
Inner Join tblSoftware On tblAssets.AssetID = tblSoftware.AssetID
Inner Join tblSoftwareUni On tblSoftware.softID = tblSoftwareUni.SoftID
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
Where tblSoftwareUni.softwareName Like 'x' And
(tblSoftware.softwareVersion Not Like 'y%' Or
tblSoftware.softwareVersion Not Like 'z%') And tblAssetCustom.State = 1
Order By tblAssets.Domain,
tblAssets.AssetName