Sorry to hear that your system went down.
As for getting a copy of 2012, don't bother, it has many problems with compatiablity. If you can find AutoCad 2009, that would be the one to use. It is the most stable since 2008 release.
Autocad 2000 full version dosen't require a key code and can be loaded onto any xp or win 7 64bit computer. You just have to make sure that your Win 7 installation can run 64 and 32 bit programs.
I will try to locate you a copy of the Acad 2000 version if you want.
Carl