Since Raw Shooter (Pixmatic) has now been aquired by Adobe, and I don't think they are offering the free version anymore. If you have RSE you can work around the lack or support for new cameras by using Adobe's free DNG converter for Raw files, then using RSE for development. A good free viewer that supports RAW is Fastone Image Viewer. It also allows you to edit in a number of other editors, while using Fastone as a browser. So if you have multiple editing programs you can quickly switch back and forth. Doesn't eat up a lot of system resources either.
http://www.faststone.org/FSViewerDetail.htm
Also there is GIMP which also works for Linux...Irfanview which a lot of people use. You can try Adobe Lightroom Beta (which is free for a while - but won't be) If you do a Google search these are easy to find.
It's too bad about Raw Shooter being gobbled up, It was a great program.