Advanced SELECT For A Newbie

I have a table full of Latitudes, Longitudes, address, customername, etc. , I need to grab some input(Latitude, Longitude, range) from the user.  So now I have a source lat, long(user) and destination lat, long(rows in dbase).  I need to take the 2 points and compute a distance from the user given lat, long to every lat, long in the database and check that distance againt the range given from the user.  If the distance is below the range, I need to put that row into a temp table and return the temp table at the end of the stored proc.

 As of right now I am completely lost and need some guidance.
 I would also like to be able to add the computed distance to a table.  Here is the function and stored procedure i have so far...
ALTER PROCEDURE [dbo].[sp_getDistance] 
     @srcLat        numeric(18,6),
    @srcLong    numeric(18,6),
    @range        int
AS
BEGIN
    SET NOCOUNT ON;

    SELECT * FROM dbo.PL_CustomerGeoCode cg
    WHERE dbo.fn_computeDistance(@srcLat, cg.geocodeLat, @srcLong, cg.geocodeLong) < @range

END
 
CREATE FUNCTION fn_computeDistance
(
    -- Add the parameters for the function here
    @lat1        numeric(18,6),
    @lat2        numeric(18,6),
    @long1        numeric(18,6),
    @long2        numeric(18,6)
)
RETURNS numeric(18,6)
AS
BEGIN
    -- Declare the return variable here
    DECLARE @dist        numeric(18,6)

    IF ((@lat1 = @lat2) AND (@long1 = @long2))
        SELECT @dist = 0.0
    ELSE
        IF (((sin(@lat1)*sin(@lat2))+(cos(@lat1)*cos(@lat2)*cos(@long1-@long2)))) > 1.0
            SELECT @dist = 3963.1*acos(1.0)
        ELSE
            SELECT @dist = 3963.1*acos((sin(@lat1)*sin(@lat2))+(cos(@lat1)*cos(@lat2)*cos(@long1-@long2)))

    -- Return the result of the function
    RETURN @dist

Thanks,
Kyle