if you have access to another computer you can make this very easy -
put your HDD in another system temporarily and copy the contents of YOUR c:\windows\repair into YOUR c:\windows\system32\config
or
if you can GET a windows installation disc -
boot from the cd
at the first setup screen press ENTER to install windows
press F8 to accept the agreement
and then press R to do a repair install if you are given the option (none of your data will be harmed)
(if you have a pc repair shop local to you drop in and ask for a copy of xp home OEM.. most places will burn you a copy of the media for a buck or free.. (they'll also try to convince you to bring the system to them for 50-100$.. don't get into conversation just ask for the disc)