Greetings,
 
There is no point in losing a legal Windows license in order to play with Koha in development.
Install virtualbox. (www.virtualbox.org)
Download the latest Debian ISO.
- I typically recommend using torrents for this, because internet connections are lousy sometimes.
http://www.utorrent.com/intl/en/downloads/win
http://cdimage.debian.org/debian-cd/8.6.0/amd64/bt-cd/debian-8.6.0-amd64-netinst.iso.torrent (64-bit)
http://cdimage.debian.org/debian-cd/8.6.0/i386/bt-cd/debian-8.6.0-i386-netinst.iso.torrent (32-bit)
- I typically stick with the 64-bit version.
 
I then create a VM based on the ISO in virtualbox.
And then once that VM is up and running, I treat it as my machine to install Koha.
 
I like to use Putty (https://the.earth.li/~sgtatham/putty/latest/x86/putty-0.67-installer.msi) to connect with the VM, because it makes cutting and pasting easier.
I also install sudo on the VM
$ su -
{root password}
# apt-get install sudo
...
# adduser {user name} sudo
# exit
$ exit
-- log back in.
That way, I can follow the installation instructions more easily.
 
I too have tried various native installations of Koha to Windows, but given the technical issues, running a VM or losing your Windows is the only way currently.
My issue has always been a lack of Perl libraries. I suspect there exists a refactoring which would run natively, but that would be a huge undertaking for such a small gain.
 
GPML,
Mark Tompsett