In my last column, I discussed the importance of the server in the server-based computing equation. I said that if you're making the case for server-based computing in your enterprise, it's important that The Powers That Be understand that the model is most often about centralizing applications and leveraging resources, not about replacing desktop PCs with thin-client devices. Sometimes, however, server-based computing is about thin clients. For instance, when PCs are Not a Good Idea, such as at sites with a lot of dust or vibration or sites with space or hands-on support limitations, you can turn to server-based computing to avoid using PCs. Clean rooms and kiosks are examples of such environments.

That's the physical case for Windows-based terminals (WBTs). What about the financial case? Is it advantageous to use PCs or terminals in a thin-client environment? The confines of this column won't permit me to address all the considerations, but we can discuss some of the questions that you should ask yourself.

First, consider the price of the terminals. How much do the models you're looking at cost? Is management software available for the terminals (if not, you should consider terminals that do offer management software), and how much more will you have to pay for it? Do the terminals come with all the parts you need? I found one terminal model that didn't include a power cord, a keyboard, or a mouse because the manufacturer assumed that its customers were replacing existing desktop machines and would have all of those accessories. (By the same token, some terminals come with monitors—something to look for before you dismiss a terminal as too expensive.)

Is the performance you might realize from a terminal solution really worth it? Modern WBTs are optimized for high-speed graphical output in ways that older PCs simply weren't—older PCs don't have the graphical acceleration or offer the 100Mbps network connections that many modern terminals do. And if users don't need access to locally installed applications, WBTs can save you the time you would have spent fixing broken hard disks and deleting games. However, an advantage of server-based computing is that it lets users access OSs and applications that their computers couldn't otherwise support, without paying for upgrades. Given the application set for your thin-client environment, which would be most cost-efficient for you: replacing older PCs with WBTs that offer better network and graphics support, upgrading the graphics and network capabilities of the existing PCs, or working with your PCs as they are? Before you answer, think about how you might better spend the time it will take you to install new video or network cards in 5000 desktop computers.

What about licensing the OS versus licensing the terminal-server access? Windows NT Workstation comes with a Windows NT Server 4.0, Terminal Server Edition (TSE) client access license; Windows CE, the OS that most modern WBTs use, does not, but the terminal price includes the Windows CE license. And while you're considering how much it will cost you to upgrade and manage client PCs, think about whether you can realistically run all your applications from a terminal-server environment anyway.

There are times when terminals are the way to go. If you're trying to provide a locked-down environment that prohibits unapproved application installations, if you have to offer computing power in a location that is PC-unfriendly, or if you're trying to provide high-end graphics support in an environment that currently consists of 5-year-old 486s, terminals are your best choice. However, if you don't necessarily need terminals to make your environment work, then pick apart the costs of the terminals and weigh the benefits against the advantages of keeping your existing PCs.