I personally don't know Quest's Foglight, but even so a got to the product page to learn a little about it. It seems to be free to up to 100 device. If it fits your environment, I would give it a try...
If you want, try <a href="http://www.mikrotik.com/thedude.php">The Dude</a>.
It is a completely free Network Monitoring Solution which can monitor windows, linuxes, routers and every SNMP enabled device. It also have an embedded Syslog server and much more...
Some of it's features include:
Auto network discovery and layout
Discovers any type or brand of device
Device, Link monitoring, and <b>notifications</b>
Allows you to draw your own maps and add custom devices
Supports SNMP, ICMP, DNS and TCP monitoring for devices that support it
Individual Link usage monitoring and graphs
Direct access to remote control tools for device management
Supports remote Dude server and local client
Runs in Linux Wine environment, MacOS Darwine, and Windows
Depending on your need to monitor, it might worth a try.