Visio, Microsoft's powerful diagramming tool, and networking are like chocolate and peanut butter. At first they seem like an unlikely blend, but when you mix them together you get something arguably tastier than either one alone.

Fluke Networks and Microsoft both offer products that add network mapping to Visio Professional 2002, with subtle differences. The combination of Visio Enterprise Network Tools 2002 (ENT) and Visio Professional 2002 carries a list price of $999, about what you'd pay if you bought Visio Professional 2002 separately ($549 list) and added Fluke's LAN MapShot diagramming software ($499 direct).

Diagrams produced by a combined system based on Visio include the configuration of virtual local area networks and the IP and Ethernet address of every networked device, as well as its make and model (provided that information is in the device's management information file). Visio's library has images of hundreds of different products, and the program uses the right image if the device is identified. In practice, the relative success of the AutoDiscovery feature depends on the segmentation in your network: Neither product combination can diagram what it can't see. Also, network devices with internal management—ideally an SNMP management information base (MIB)—yield a lot more information.

ENT is best for mapping extended corporate networks, while LAN MapShot excels at drilling into the details of a local network within a single domain. ENT can span multiple domains, and if you are implementing or managing directory services on the network, it can import LDAP information and depict the appropriate directory information with each device. LAN MapShot works through switches to uncover and display the details of printers and other attached devices.

Using Visio at PC Magazine Labs over an extended period of time, we found that every diagram is improved by editing, and the more information you add (such as physical location), the more complete the diagram becomes. Still, either system alone creates impressive diagrams that are immediately useful.