It really shouldn't say the title like this as all what I am talking about here is just one wonderful tool that does this kind of job for fee. However, since my first post named like this it would be easy to named as the same to keep it consistent.
On my first post, I only mentioned the software called ManageEngine OpManager 5.5 from AdventNet but didn't put any comments on it because I haven't got chance to do a test even a quick one at that time. Now, today I finally got the time to get it downloaded and installed on my test computer. Looks really good!! The installation procedure is very straightforward but before running it you have to do some configurations on the server you want to monitor to load the SNMP so that the OpManager could retrieve the data from the monitored server. That is something cool actually because a lot of similar software I used before require to install a client/agent on the monitored server to be able to send or receive the data. Windows 2000 and 2003 Server even NT all have this SNMP component available by default but you have to install it from Add/Remove Programs. Once you have this all set up, you can either launch a windows client or web-based client to manage it, add nodes, alerts, monitors, etc. a lot of things you can monitor from the program.
The another thing about this tool is the cost, free for monitoring 10 nodes, $795 for one user to monitor unlimited nodes, very very attractive for the small, and medium business.
ManageEngine OpManager 5.5