NEFs show in Windows explorer as previews when you install the latest Nikon Pictureproject, I'd guess Canon may have something similar.
They will also open in PS
After using PSP7 since about 2000, PS
Elements 4 is a major improvement. As I don't do really fancy stuff (I try to get things right without electronic trickery) it's enough for me and at the price it can't be beat compared to PS
CS2 which cost something like 15 times as much.