Not pretty but give you what u want
declare @d datetime
declare @w int
set @d = '2003-01-01'
set @w = 5
set datefirst 1
set @d = @d-(datepart(dw,@d)-1)
select @d+((@w -1) * 7),(@d+((@w -1) * 7))+6
Far away is close at hand in the images of elsewhere.
Anon.