Without getting into windows I know no way to retrieve the keys. The other option is to do a Parallel Installation
. This would make a second installation of windows within the existing partition and allow you to hopefully then run one of the above mentioned programs.
Another option is to use a Linux Live cd
to get to the hd to backup the data. Now I don't know if this will allow you to get the serial number though.
I am going to supply the alternatives instructions once you can let me know which way you would like to proceed.