The best program for this is PAINT.net. It is very effective and free, and requires no plugins to open a .dds file. I have photoshop, but i prefer to use PAINT.net.
http://www.paint.net/
Hi, below is a link to a page with what looks like most of the .dds tools. Only one I don't see is the plugin to allow you to view .dds files as thumbnails in windows explorer.