Counting Records Using A WHILE Cycle

I have a table that contains a list of departments (about 50) and another table that contains helpdesk tickets, each record storing the ID of the department sending the ticket. So I'm trying to count how manay tickets per department, I tought of using a subquery and a WHILE cycle but Its just not happening..I sketch up this query:

Code:
WHILE (SELECT MAX(DepartmentID) AS c FROM dbo.tblDepartment) i < i.c
BEGIN
SELECT COUNT(DepartmentID) AS DepartmentCount
FROM dbo.tblTask
WHERE (DepartmentID = @Variable)
END

how could I build this query or what better way of doing the job there are...