Here's something you can play with, changing table/field names as necessary. Since you might want a little advance notice, it returns those who have birthdays during a given month.
SELECT LastName, FirstName, DatePart("m",[dob]) AS bMonth, DatePart("d",[DOB]) AS bDay,
Trim([firstname])+" "+[lastname] AS Expr3, DateSerial(Year(Now()),([bMonth]),[bDay]) AS Birthday
FROM tblStaff
WHERE (((DatePart("m",[dob]))=[enter month (1-12)]))
ORDER BY DatePart("m",[dob]), DatePart("d",[DOB]);