Integer to date in SQL Server 2005

I need to create a loop to pull records that are within a quarter from 2006 to the present.  I have created a routine to increment the months and years using integers to get the begin and end dates for each quarter.  I can't seem to use the integers to create a date.

DECLARE @EarnYear int,

@Beginer int,

@First int,

@QtrBegin datetime

SET @EarnYear = 2006

SET @Beginer = 1

SET @First 1

SELECT (CAST(CAST(@EarnYear as char(4)) +

right('00' + cast(@Beginer as varchar(2)),2) +

right('00' + cast(@First as varchar(2)),2) as datetime) as @QtrBegin

Can anyone help?  Thanks.