have a look at free UserDirectory module from www.effority.net or in your own module use BCL calls instead of directly accessing the database.

SELECT     dbo.Users.UserID, dbo.Users.Email, dbo.Users.DisplayName,
                          (SELECT     propertyvalue
                            FROM          userprofile
                            WHERE      propertydefinitionid = 27 AND userid = dbo.users.userid) AS City,
                          (SELECT     propertyvalue
                            FROM          userprofile
                            WHERE      propertydefinitionid = 35 AND userid = dbo.users.userid) AS IM, dbo.UserPortals.PortalId
FROM         dbo.Users INNER JOIN
                      dbo.UserPortals ON dbo.Users.UserID = dbo.UserPortals.UserId
WHERE     (dbo.UserPortals.PortalId = 2)