So, you installed winxp right, then take out the installation media, boot into bios and select to boot from hdd in the same place where you selected to boot from dvd and save and continue the boot and it should work.
Note: The boot drive must be set to hdd. Remember that it wont show hdd in the bios but something like WDC(and then the model no.) if western digital cavair hdd or SB(and then the model no.) if Seagate Barracuda,etc. If it only shows hard disk drive, then it could be that the SATA cable has got loose. Try this and let us know.