Jon,

Have you tried the CASE expression? Something like...

SELECT Timehd.empid, Timehd.date,
'newcolumn'=CASE
WHEN Timeitms.timeout>17 AND Timeitms.timein>17 THEN Timeitms.timeout-Timeitms.timein
ELSE Timeitms.timeout-17
END
FROM prewel!timehd INNER JOIN prewel!timeitms
ON Timehd.timecrdno = Timeitms.timecrdno
WHERE Timehd.date = ?m.dNextChkDate-13
AND Timeitms.jobno <> "LUNCH"
GROUP BY Timehd.empid, Timehd.date
HAVING Timeitms.timeout>17
ORDER BY Timehd.empid

HTH