Dramatic increases in the number of transistors that can be integrated on a chip will make the hardware more susceptible to radiation-induced transient errors. Highend architectures like the IBM mainframes, HP NonStop or mission-critical computers are likely to include several hardware-intensive fault tolerance techniques. However, the commodity chips which are cost- and energy-constrained, will need a more flexible and inexpensive technology for error detection. Software approaches can play a major role for this sector of the market because they need little hardware modification and can be tailored to fit different requirements of reliability and performance.