Though Linux works for me and many other users, its sheer power and generality is its Achilles' heel. If you know what you are doing, you can buy a cheap PC from any computer store, throw away the Windows discs that come with it, turn it into a Linux system of mind-boggling complexity and power. You can hook it up to twelve other Linux boxes and make it into part of a parallel computer. You can configure it so that a hundred different people can be logged onto it at once over the Internet, via as many modem lines, Ethernet cards, TCP/IP sockets, and packet radio links. You can hang half a dozen different monitors off of it and play DOOM with someone in Australia while tracking communications satellites in orbit and controlling your house's lights and thermostats and streaming live video from your web-cam and surfing the Net and designing circuit boards on the other screens. But the sheer power and complexity of the system--the qualities that make it so vastly technically superior to other OSes--sometimes make it seem too formidable for routine day-to-day use.