Let me start by saying I do not possess much computer knowledge. I've been under the hood a couple times on limited repairs on the PC built for me by a friend.
I recently unpacked and set up this XP powered PC that had not been used in seven months. Prior to that time it served me well for 5-6 years. Several years ago it was successfully converted from "98" to "XP" and ran smoothly with no problems.
It seemed to be booting up fine, the BIOS read the drives and configuration. But then a DOS message appeared saying, "system boot failed, insert boot disk and press enter."
I don't have a boot disk (dumb, I know) so I inserted the original XP disk.
The attempt to reload XP went ok until it got to the "Welcome To Setup" screen. I pressed enter and got back another message, "did not find any hard disk".
Which left me where I started. BIOS sees hard drives, Windows Setup doesn't. PC sits idle.
If anyone can unravel this problem please do not hesitate to contact me. I am frantic.
Any and all suggestions are welcome.

even though BIOS can see the hard drive it's possible that the hard drive has some type of problem. If you want to attempt this yourself the first thing I would recommend would be to try a different hard drive or try the drive in a different computer. if that is not an option then go to the hard drive manufacturer's website and download their hard drive diagnostic software so you can test the hard drive.

this would just be the first steps, if you find the hard drive to be good then post back and we can take it a step further

Hi one thing I have found with the hard drive not beeing seen is to disconnect the drive from the motheroard and power supply, reboot the pc. Turn off the pc and reconnect to motherboard and power supply. power up the pc. This works about 80% of the time. Back up any data and think about buying a new drive.
Hope this help and good luck