WHERE float_column > = 0.0 

DECLARE @tbl TABLE ( float_column FLOAT )

INSERT INTO @tbl
SELECT 0 UNION ALL
SELECT 0.001 UNION ALL
SELECT -0.001 UNION ALL
SELECT -1110 

SELECT  *
FROM   @tbl
WHERE float_column > = 0.0 

/* result set
float_column
0
0,001
*/

DECLARE @tbl TABLE
(
	DATE DATETIME,
	amount DECIMAL(10,2),
	interest FLOAT
)

INSERT INTO @tbl
SELECT '2009-04-10 00:00:00.000', 450.00, 00.23 UNION ALL
SELECT '2009-04-10 00:00:00.000', 451.00, -1.20 UNION ALL
SELECT '2009-04-10 00:00:00.000', 460.00, 2.5

SELECT DATE, amount, interest FROM @tbl WHERE interest > 0 
/* result set
date	amount	interest
2009-04-10 00:00:00.000	450.00	0,23
2009-04-10 00:00:00.000	460.00	2,5
*/