Aircrack-ng is an 802.11 WEP and WPA-PSK keys cracking program that can recover keys once enough data packets have been captured. It implements the standard FMS attack along with some optimizations like KoreK attacks, as well as the all-new PTW attack, thus making the attack much faster compared to other WEP cracking tools.
Available in pre-compiled binary for Windows, Mac OS X and source code should you wish to compile it yourself.
I'm sure there are others examples out there too that run on Windows. Of course, if you run virtualisation software on your Windows box then your argument is further obsolete, same goes for any tools that make a source code format available !
You should really always use the highest available, which for the home user these days is WPA2-PSK, which offers additional protection over plain WPA-PSK.