Conditional Processing From A Common Table Expression (CTE)

I want to do conditional processing depending on values in the rows of a CTE. For example, is the following kind of thing possible with a CTE?:


WITH Orders_CTE (TerritoryId, ContactId)
AS
(
SELECT TerritoryId, ContactId
FROM Sales.SalesOrderHeader
WHERE (ContactId < 200)
)
IF Orders_CTE.TerritoryId > 3
BEGIN
/* Do some processing here */
END
ELSE
BEGIN
/* Do something else here */
END

When I try this, I get a syntax error near the keyword 'IF'

Any ideas? I know this kind of thing can be done with a cursor but wanted to keep with the times and avoid using one!