I use the Windows Texture Viewer, DDS thumbnail viewer, and the PhotoShop plugin (with Paint Shop Pro). I've never had an issue with full-color DDS files not opening in full-color with any of these utilities.
http://developer.nvidia.com/object/n...ure_tools.html
Edit: Keep in mind that some DDS files are meant to be greyscale, and those are typically bump or glow maps. The DDS files that are meant to be in color will usually have a "_c.dds" suffix (but not always...sometimes there's no "_c").