The latest version of digiKam is available for Windows. If you are looking for a capable alternative to the expensive proprietary offerings you may want to give it a shot.
You can get if from the standard SourceForge repository. Here is the official announcement:
digiKam 2.2.0 Installer for Windows Scribbles and Snaps
And here is a link to the SourceForge download page:
digiKam - Browse /digikam/2.2.0 at SourceForge.net
I use digiKam for all my RAW processing. I like working with it better than with Photoshop. It is nice to finally have it for Windows as well. It is a large download (about 220 MB.) But, I think it is worth it.
That having been said, please note that the Windows version is still experimental. Also, if you are on Windows 7 64bit, you may want to run in XP SP3 compatibility mode (I haven't tried it on 32 bit). For full functionality you still need to run it in Linux. Still, it already works quite well.
Here is an article talking about this version of digiKam that you can read if you want to decide if it will be worth your while:
digiKam 2.0 beta review – the ultimate open source image editor | Linux User
You can learn a lot more by going to the digiKam official website:
digiKam - Photo Management Program | Manage your photographs as a professional with the power of Open Source
Enjoy!