|Well first you want to go to the namebrands vendors website look up your model and see if they have any xp drivers for your pc. If not you are going to have to go into your device manager and find out who makes your graphics card, sound card, chipset drivers and look at the models of those devices and go to those modesl websites and search for that model driver for xp.|
Once you do all that burn a copy of those drivers onto a cd.
Then use a free program called killdisk, burn that onto a cd and load it as soon as you boot the machine and erase all the partitions you see there.
once that is done reboot and load the windows xp cd on your machine to install it and you're done. After xp is installed install all the hard ware device xp drivers you got off of from the nambrands pc website or the hard ware vendors website and you're done.
Without knowing who makes your pc and what model it is, i couldn't make it any easier then this to explain to you how you do it.