A recent thread in the CertTutor.net Live! The Real World—General forum mentions a helpful utility that I use every day: VMware's Vmware Workstation. You can use VMware and Connectix's Connectix Virtual PC for Windows to run a computer simulation within your PC. Let's delve a little deeper into the advantages that these utilities offer.

The virtual machines (VMs) that these applications create are nearly identical to real computers. A VM includes a BIOS and interfaces that you can add and remove. My VM has a SCSI adapter for virtual SCSI drives, two IDE channels for up to four IDE devices, a Sound Blaster-compatible sound card, multiple network cards, serial ports, parallel ports, and more. You can connect most of these interfaces to your actual equipment, or they can exist virtually. For example, you can link a VM hard disk directly to a physical partition on your hard disk, or it can exist as a file that acts like a hard disk.

VMs are invaluable tools for IT students studying for the next certification or preparing for the next big application rollout. A great advantage of using a virtual hard disk is that you can reset it and return it to an earlier configuration. This feature lets you try different scenarios on a base installation, then return the VM to the base installation after each run-through. If you make a mistake, no problem—click a button and begin fresh without having to reinstall the OS.

Networking capabilities are another advantage of working with VMs. You can use virtual network adapters to network VMs together with any protocol that real adapters use, even if your VMs are completely isolated from your actual network. But you can also link VMs to your network and the Internet by bridging through your real network card or using Network Address Translation (NAT). You can practice working with DHCP, DNS, and WINS without interfering with the real thing. RRAS is a significant component of Microsoft Exam 70-216: Implementing and Administering a Microsoft Windows 2000 Network Infrastructure and Exam 70-276: Implementing and Administering a Microsoft Windows .NET Server Network Infrastructure. With a virtual network, you can set up routers and links without having to scrounge up extra computers, network cards, and cables—all within the confines of one desktop workstation.

Even if you're not preparing for a certification exam, VMs can be a godsend. If you're like me, you prefer to use the latest OS on your desktop, both because the new OS is usually better than its predecessor and because it gives you a chance to get used to new features and foibles. When remote clients or users ask for help with their systems, you typically have to talk them through the solution from memory or access a machine with the appropriate OS. With a VM, you can immediately see the menus and dialog boxes your user is seeing.

Another real-world use for a VM is application testing. You've probably spent untold hours tweaking your workstation to get it just right, and you don't need the aggravation of having to rebuild it because the "neat" game your Aunt Mame sent you decided to corrupt DLLs. With a VM, you can quickly determine whether an application will install correctly and evaluate the application's usefulness. When you're finished, a click of a button returns the VM to its previous state, as if the application never existed. Similarly, you can test files for viruses. You can also install viruses to determine what damage they might cause and practice removal techniques before responding to an important client's plea for help.

Other great uses for VMs include testing dynamic disks, server clustering, and RAID configurations. You can use VMs to perform product demonstrations for clients, experiment with unfamiliar OSs, and, of course, prepare for exams. To learn more about VM software and its uses, see the CertTutor.net Live! discussion forums and the following vendor Web sites: