Intelligent network monitoring systems (commercial/open source, what have you)

Howdy, Can anyone suggest a network monitoring system that knows the difference between a cisco 1701 and a GSR 12810/6500, etc? What I mean is, many times these days there are several different sub systems you have to monitor inside of a router/switch and not just interface utilization, the "CPU", and the "RAM". Statistics such as CEF utilization, fabric utilization, PFC/DFC, various line card statistics, etc? Can anyone recommend anything other than "customize MRTG a lot" that we can use to get a better look into these systems? thanks, -Drew