An anonymous reader writes "My father is a veterinarian with a small private practice. He runs all his patient/client/financial administration on two simple workstations, linked with a network cable. The administration application is a simple DOS application backed by a database. Now the current systems, a Pentium 66mhz and a 486, both with 8MB of RAM and 500MB of hard drive space, are getting a bit long in the tooth. The 500MB harddrives are filling up, the installed software (Windows 95) is getting a bit flakey at times. My father has asked me to think about replacing the current setup. I do know a lot about computers, but my father would really like the new setup to last 10-15 years, just like the current one has. I just dont know where to begin thinking about that kind of systems lifetime. Do I buy, or build myself? How many spare parts should I keep in reserve? What will fail first, and how many years down the line will that happen?"