In reality, the small surge of power created when some devices are turned on is vastly smaller than the energy used by running the device when it is not needed.
Modern computers are designed to handle 40,000 on-off cycles before failure, and you're not likely to approach that number during the average computer's five- to seven-year life span. In fact, IBM and Hewlett Packard encourage their own employees to turn off idle computers, and some studies indicate it would require on-off cycling every five minutes to harm a hard drive."
My friend was telling me leaving it on will save more money because the boot up spends alot of electricity in the few seconds it starts up.