That is the solution that i have implemented for our little environment that consists of about 50-ish solaris (8 and 10) servers, 80-ish windows servers, about 500 linux servers, and 40-odd cisco switches. Hobbit handles all host monitoring: availability, services, and a bunch of custom scripts written for it to check various aspects of our HPC grid, plus the SMS sending through an old nokia connected to the comm port of a solaris box. Smokeping is there to check latency, and cacti primarily for network traffic volume, and a custom module for FlexLM licenses. Works like a charm