If you shoot RAW files at all (they’re called NEF on Nikon cameras and CRW on Canon cameras) then you likely have a system for dealing with them. Because RAW files are unstandardized, the RAW format will vary from company to company, and from camera to camera. Nobody has really settled on a “standard” RAW file yet, which upsets a lot of photographers. RAW will continue to remain a non-standard format, so long as the camera company continues to stand behind the format, and there is no good reason to standardize.
But it would be nice to just be able to see those pictures in Windows, and open them in a preview pane without having to open Photoshop or Capture. That’s where the new Microsoft RAW Image Thumbnailer and Viewer for XP comes in. It’s a fairly small installation, which resembles the Microsoft Picture and Fax Viewer, but is designed for a multitude of RAW files.
You can download the viewer at the Microsoft site.

