There are two ways.
Long, tedious way: take each texture into your image editor, I use paint.net it's free,and do a "save as" .jpg. It will have the same name, so show up right beside your .dds, thus allowing you to view what the texture is.
Lovely, no time way: google Mystic Thumbs. Its free, although it places a little water mark on the image, and it allows you to view the .dds in the folder.
It's 25 bucks if you want to buy it. It seems like someone posted a different program somewhere that was similar that they liked, but stupid me didn't bookmark itand now I can't remember where it was.
Here's the info on those two methods:
http://ts3cc.forumotion.ca/t281-tutorial-source-texture-organization
http://ts3cc.forumotion.ca/t360-mystic-thumbs-dds-viewer-for-windows
