xp wont boot, system restore w/o boot?

[xShrimp]

my computer was working fine yesterday, but this morning it was shut down, i knew i left it on last night. when i turn it back on, it said that my windows\system32\config\system was missing or corrupted, so i tried safe mode. safe mode didn't work because it still said that the file was missing corrupted. every mode that ive tried always ended up the same way and says to repair, but is there an alternative instead of repairing such as a system restore w/o booting? because i dont want lose anything on my computer because it is a 250GB (85% full)

EDIT: i went through my dad computer and found his system file, is there a way for me to replace it? i do have a 40gb hdd unplugged in my computer, should i install xp on there and replace the system file like that? whats the difference in the system file coming from different computers? (im planning to take it from a sony vaio xp media center)

[xShrimp]

Repair installs you won't lose your computer data.

but if i copy my system file from my dads computer to my computer with xp running on another hdd, would it work?