For checking out images, I recommend the program called IrfanView, it opens just about any type of image file you can think of plus allows limited editing on things such as brightness, colors etc. Its main purpose is however opening images to view them. I believe however, you would need to manually get the dds plugin for it, as I have not updated in a while so I dont know if its included now.
Yes irfanview is an excellent free program that will let you see dds files. You don't need a plug-in as it opens dds as is already.
http://www.irfanview.com/
Gimp is a free program for editing dds file ( you'll need the plug-in). this will let you do many things that photoshop can do. In this case you can desaturate and change the hue or color of the image to make it fit your game. It's the first step to learning the fun art of making textures. I believe Connary prefers Gimp Over Photoshop for making textures.:foodndrink:
http://www.gimp.org/