Systems Management Package

I am looking for a good Systems Management package. I’ve used HP Openview, worked a little with NetIQ, but I also don’t want to break the bank. I have 2 scenerio’s one is a 400 employee company and the other has 5 employees. My goal is to offer an affordable solution for management. An engineer or employeee is paged if a server goes down. I need to be proactive with the management. Any recommendations?