What is wrong with a PC tat does not recognize an iPod even if it is running WINXP?

Answer 1

USB port or cable is damaged or disabled.

Try the same cable on another machine with the same ipod to see if it works. If it doesn't then the problem is with your cable or ipod, replace the cable, try again, if still problem then it's your ipod.

However, if it works on another machine check your bios to see if usb ports are disabled, check your drivers to see if they are up to date. Do other devices work on that usb port?