Ok, this is strange:

DECLARE @FirstSat VARCHAR(11)

DECLARE @Temp VARCHAR(46)
SELECT @Temp = '2010-04-Apr'
DECLARE @DATE DATETIME
 
SELECT @DATE = LEFT(@Temp,7) + '-01'
 
SELECT TOP 1 @FirstSat = DATEADD(dd,number,@DATE)
	FROM master..spt_values
	WHERE type = 'p' AND
		  DATEPART(dw,DATEADD(dd,number,@DATE)) = 7
	ORDER BY 1 ASC

SELECT @FirstSat


/*

DECLARE @Temp VARCHAR(46)
SELECT @Temp = '2010-04-Apr'
DECLARE @DATE DATETIME
 
SELECT @DATE = LEFT(@Temp,7) + '-01'
 
SELECT TOP 1 DATEADD(dd,number,@DATE) AS FirstSat 
	FROM master..spt_values AS FirstSat
	WHERE type = 'p' AND
		  DATEPART(dw,DATEADD(dd,number,@DATE)) = 7
	ORDER BY 1 ASC
*/

Run both queries. They return different formats. I need back a DATETIME.