I Like SolarWinds (Score 1)

For the price, I am a big fan of SolarWinds Network Performance Monitor (NPM)and ipMonitor. Together, these give me the ability to track and monitor as many devices as I want. They both have network discovery, and can monitor network devices, servers, workstations, and applications. I have not tried the Application Monitor add-on for NPM as a replacement to ipMonitor, but it looks like it would work very well. I have written several c# scripts to augment ipMonitor for the custom applications I need to monitor. The only downside I can see for you is that it these are Windows based productions, and NPM requires Microsoft SQL 2005. I love the map capabilities in NPM and the graphs it makes. I am able to alert on any OID I collect data on, which is a plus. Also, NPM has thousands of MIBs already installed, which makes finding an OID much easier. Best of all, NPM supports OID tables, which makes my monitoring very dynamic. I have, for example, created an alert on disk partitions getting more then 95% full. I do not have to worry about making an monitor for each possible partition, or even worry about how many partitions are on a server. I just monitor the OID table. As long as I have set SNMP properly (of course) I see all the partitions I care about. ipMonitor I use mostly for application monitoring. In this respect, it is very nice, since I can execute custom scripts. For your scenario, I would seriously look into NPM. This is a very easy product to learn, very powerful, and can be fairly cheap to implement.