This is what I used specifically
SELECT query.Domain, query.Username, COUNT(query.Computername) AS Expr1, tblcomputers.Computer
FROM (SELECT DISTINCT Computername, Domain, Username, ADsite
FROM tblCPlogoninfo
GROUP BY ALL Computername, Domain, Username, ADsite) AS query INNER JOIN
tblcomputers ON query.Computername = tblcomputers.Computername
WHERE ADSite LIKE '%<YOUR AD SITE HERE>%'
GROUP BY query.Domain, query.Username, tblcomputers.Computer
ORDER BY tblcomputers.Computer