Try Catch with RollBack

BEGIN
TRY
BEGIN TRANSACTION
-- Update blah blah blah
-- If we got to this point, we are good
COMMIT

END TRY

BEGIN

CATCH
-- Thank you GuysFromRolla for this code.

IF @@TRANCOUNT > 0
ROLLBACK

-- Raise an error with the details of the exception.

--note: * I have heard ASP.NET will give the Raiserror message...

DECLARE @ErrMsg nvarchar(4000), @ErrSeverity int
SELECT @ErrMsg = ERROR_MESSAGE(),@ErrSeverity = ERROR_SEVERITY()
RAISERROR(@ErrMsg, @ErrSeverity, 1)

END CATCH

END