Your friend has a Windows XP desktop system that contains important data. He frantically calls you to say that when he turns on the computer, the lights on the front panel light up and he can hear the fan spin for a moment and then all goes dead. His most urgent problem is the data on his hard drive, which is not backed up. The data is located in several folders on the drive. What is the quickest and easiest way to solve the most urgent problem? recovering the data? List the major steps in that process.

Remove the hard drive from the computer and connect it into an USB hard drive adapter. Then connect this adapter and hard drive into a working computer's USB port. This computer will see this as an external storage device, then open the various folders and files on this external hard drive and copy/backup the data.
If the computer cannot detect this USB external storage device then most likely the hard drive gas failed.
Replace the hard drive and check to if the BIOS can detect the hard drive, if OK then check the RAM and you may need to reinstall Windows to get the computer working again.

It seems that that there is some problem with the power supply or in the mother board. Or there might be minor problem ... but for the data it seems it's safe. but you can get your data by removing the hard-drive from the faulty computer and attach it with working one. In this way you can get you data back. But best way is to get your computer fixed up. Your data is all safe.

Without trying any experiment I suggest that your friend take the hard disc and recover all the data after attaching the hard disc to a PC or get help from any PC service to give you the cables for transfering to a laptop through the USB.