small inaccuracy in your post ... it should read
the kids just used to use it for playing pc games on
you might get away with borrowing a friend's disc ... it may not ask for the serial (which I assume you also don't have?)
it's possible that somewhere on the Hard disc there is an C:\WINDOWS\i386 folder which contains the files you need
otherwise ... take smallest child ... place in basket ... take to local market ... see if you can get enough for a replacement disc
I like kids ... just never seem to be able to eat a whole one!