MySQL monitoring tools

I've used Nagios in the past with success. It's very extensible (over 200 add-ons), relatively easy to use and lots of reports. A negative would be the initial setup.

This may not meet all your needs, but we use Nagios to keep an eye on our servers. It it's very simplest level it can just monitor whether or not a server is up, but with agents installed it can also monitor CPU load and anything else you can determine locally. Even if an agent doesn't exist to do exactly what you want, they are quite easy to write, I've written a few highly customised ones over the years with very little effort. We use Nagios on Linux, but it does have Windows support, so it's worth considering anyway.

Nagios is a fairly large solution though, requiring a server, and is designed for monitoring a whole network of machines and servers than for monitoring just one single server. It is free and open source though.