Find Out If Current User Is Member Of A Role

I need a stored procedure to find out if the current user is a member of a certain role.

I want to pass the role name and return a bit to tell whether he is a member or not.

I have this code to list the groups the current user is a member of but I don't know how to search or do a "SELECT FROM" on the results.

DECLARE @usr varchar(32)

SET @usr = USER

EXEC sp_helpuser @usr


But if the current user is a member of more than one role it returns multiple rows. So if I could do something like:

DECLARE @grpName varchar(32)

SELECT * FROM (EXEC sp_helpuser @usr) WHERE GroupName=@grpName
IF rowcount > 0 THEN
RETURN 1
ELSE
RETURN 0
END IF

I know that doesn't work so how can I do this?