Linux itself is low-cost, and this fact can be a big plus; however, the cost of the software is likely to be a small factor in the overall cost of running a computer. The TCO of Linux versus Windows is a matter of some debate, but it’s likely to be lower for Linux if experienced Linux or Unix administrators are already available to deal with the system.

All versions of Windows are largely tied to their GUIs; administering a Windows box without its GUI is virtually impossible. This linkage can make picking up Windows administration a bit easier for those unfamiliar with text-mode configuration, but it imposes some overhead on the computer itself, and it restricts the ways in which the system can be administered. These limitations are particularly severe for servers, which may not need a flashy GUI to handle mail or deliver IP addresses, except insofar as the OS itself requires these features. Linux, by contrast, is not nearly so GUI-oriented. Many distributions do provide GUI tools, but bypassing those tools to deal with the underlying text-mode configuration files and tools is usually a simple matter, provided you know where those files and tools are located and how to handle them.

In part because of Windows’ reliance on its GUI, it requires slightly more powerful hardware than does an equivalent Linux server. This factor isn’t extremely dramatic, though; chances are you won’t be able to replace a 3-GHz Pentium 4 Windows system with a 200-MHz Pentium Linux system and achieve similar performance. Linux also runs on an extremely broad range of hardware platforms—IA-32, AMD64, PowerPC, Sparc, and so on. On the other hand, in the IA-32 world, the vast majority of hardware comes with Windows drivers, whereas Linux driver support isn’t quite as complete. Linux drivers are available for most, but not all, IA-32 hardware.

Both Linux and Windows provide multiple choices for many server software categories, such as mail servers or FTP servers; however, those choices are different. The best choices depend on the server type and your specific needs. Much of this book focuses on servers that work very well for Linux and for which the Windows equivalents have problems of one sort or another—cost, reliability, flexibility, or something else.

This issue is really one of server features. Many Windows server programs are designed around proprietary or semiproprietary Microsoft protocols, or provide extended features that can be accessed from Microsoft clients. For these functions, Linux servers must necessarily either play catch-up or use alternative protocols. For instance, the Samba server on Linux does not provide the full features of a Windows 2000 or 2003 Active Directory (AD) domain controller. Thus, if you want such features, you must run either the Windows server or find some other way to implement the features you want.

Because Linux doesn’t run the popular Windows programs except under emulators, file format compatibility may be an issue. This can be a factor when you read your own existing files or exchange files with other sites (with clients, say). In the office field, OpenOffice.org provides very good, but not absolutely perfect, Microsoft Office document compatibility. Appendix B describe this issue in greater detail.