One way to manage a network is to move around from system to system, forever checking what's going on. It might be easier to use Windows Health Monitor, though, which provides the core details on up to ten of your network PCs from one convenient interface.
The program can monitor both servers (Windows 2003, 2008, 2008 R2) and desktops (XP, Vista, 7), and can track a variety of system health indicators: CPU, memory and disk utilisation, disk read and write activity, network bandwidth use, even key server applications (Exchange, Microsoft SQL Server).
The results are then available in a simple Dashboard view, which alerts you to the top three systems in terms of CPU, memory and disk utilisation.
Or you can choose a particular monitored system and view all its details (including basic system information) on a single page.
As you might guess by the monitoring of apps like Exchange Server, Windows Health Monitor is aimed at business users. The program is designed to works just as well with small home networks, though: when adding a system to monitor, for instance, you can specify either its domain or workgroup.