I found the following report in the user report's section of the forum. This will allow you to find computers that are not running the particular service that you specify in the report.
Select Top 1000000 tsysOS.Image As icon,
tblAssets.AssetID,
tblAssets.AssetName,
tblAssets.Domain,
tblAssets.Username,
tblAssets.Userdomain,
tblAssets.IPAddress,
tblAssets.Firstseen,
tblAssets.Lastseen,
tblAssets.Lasttried
From tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysOS On tsysOS.OScode = tblAssets.OScode
Where tblAssets.AssetID Not In (Select Top 1000000 tblServices.AssetID
From tblServices Inner Join tblServicesUni On tblServicesUni.ServiceuniqueID =
tblServices.ServiceuniqueID
Where tblServicesUni.Name Like '%YourService%') And tblAssetCustom.State = 1
Order By tblAssets.Domain,
tblAssets.AssetName