I think that HK Cafe is the best Chinese food in Madison (however, I make no claim that it is authentic--I'm comparing it to other Chinese-American restauarants in the area) For example, when I order sweet and sour chicken, it's actually in the sweet & sour sauce rather than just some fried chicken with red sauce on the side. The other dishes I've had there have been a distinct improvement over typical Chinese-American food too.
The downside--it is expensive for dinner. Much more so than the other Chinese places in town. I only buy this for lunch.