I agree with Stuart. Booing the home team and their players is classless. When I played sports in high school, I would have been very disappointed if my parents, family, or close friends booed my performance, even when I'd messed up. They were my truest fans. If I couldn't expect consistent support from them, where could I expect it? The fact of the matter is that cheering is a much better motivator than booing. Positive support can spur players on to do greater things much more effectively than booing ever will. This is why I'll take Gibbs over Parcell any day.
Booing the Refs on the other hand is completely appropriate, since I've never claimed to be their fan.
--Phin