TSQL substitute for MAX() string ranking
Use RANK() function

with CTE_X as 
(
  select *, 
  RANK() over (partition by Col1
             order by Col2 DESC) rnk
  from t

) select * from CTE_X  where rnk = 1 ;


For reference (BOL) http://msdn.microsoft.com/en-us/library/ms176102.aspx