Can I use windows 7 disc for windows xp recovery?

I need to follow these

md tmp
copy c:windowssystem32configsystem c:windowstmpsystem.bak
copy c:windowssystem32configsoftware c:windowstmpsoftware.bak
copy c:windowssystem32configsam c:windowstmpsam.bak
copy c:windowssystem32configsecurity c:windowstmpsecurity.bak
copy c:windowssystem32configdefault c:windowstmpdefault.bak

delete c:windowssystem32configsystem
delete c:windowssystem32configsoftware
delete c:windowssystem32configsam
delete c:windowssystem32configsecurity
delete c:windowssystem32configdefault

copy c:windowsrepairsystem c:windowssystem32configsystem
copy c:windowsrepairsoftware c:windowssystem32configsoftware
copy c:windowsrepairsam c:windowssystem32configsam
copy c:windowsrepairsecurity c:windowssystem32configsecurity
copy c:windowsrepairdefault c:windowssystem32configdefault

steps to fix a problem I’m having on an XP machine. I only have a Windows 7 32 bit disc. Would there be any reason why I shouldn’t do this and go find an XP disc instead?

I don’t see any problem at all with doing this. Those are just simple DOS commands to backup the corrupted registry files and then overwrite with good copies from the windowsrepair folder. The XP bootloader should not be affected unless you mistakenly run fixboot, fixmbr and the like from Win7’s Recovery Environment. If you want to use a GUI instead, you can also do this using a Linux LiveCD/USB.