in 2008 how do I convert a varchar to a date

I concur with Squirrel that formatting should be done on the view of the data. Dates can sometimes be pesky to work with though. The below SQL might help to understand what's happening with your VARCHAR to DATE conversions.

DECLARE @dtTimeAsVarChar VARCHAR(8)            
DECLARE @formattedDt DATE            
            
SET @dtTimeAsVarChar = '20100506'  -- Data to Manipulate            
            
SET @formattedDt = CONVERT(DATE,@dtTimeAsVarChar,112)  --- Convert to Real Date            
            
SELECT CONVERT(CHAR(10),@formattedDt,101) AS [mm/dd/yyyy]             
SELECT CONVERT(CHAR(10),@formattedDt,102) AS [yyyy.mm.dd]            
SELECT CONVERT(CHAR(11),@formattedDt,106) AS [dd MMM yyyy]            

Returns

mm/dd/yyyy            
----------            
05/06/2010            
            
yyyy.mm.dd            
----------            
2010.05.06            
            
dd MMM yyyy            
-----------            
06 May 2010            

The options for converting date and datetime data are found on MSDN at: http://msdn.microsoft.com/en-us/library/ms187928(SQL.90).aspx

this will convert your date in fieldname in varchar to data data type

convert(date, fieldname, 112)

you can use datatime if you like.

to appear as "05/02/2010" this is formatting issue. Do it in your front end application or reporting tools where the data is shown