formating

i have a compaq deskpro xe.i don’t have any disks or cd’s with it.was getting the error message “invalid system disk,replace disk and press any key.”well the only way to get this machine to do any kind of boot was with a windows 98 boot disk.after format which seemed to go ok,i would reboot and then i would get the message “PCI READ CONFIGERATION FAILURE,ABORTING INSTALLATION.”