I know this is an aged thread just over a year old, but I figured I'd throw a response out there, since this thread hadn't touched on the following tool:
http://code.google.com/p/remote-linux-monitor/downloads/detail?name=remote-linux-monitor-v1.03.jar&can=2&q=
^^^ Works great to monitor linux VPS' w/o having to install nodes or dameons therein. My monitoring machine here at the house is a Win8Pro x64 VM on a Win7Home x64host and I can monitor multiple Linux VPS' concurrently using this tool.
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