exdragon,
There is a very, very easy way to do what you want, as long as you're running a PC with Windows XP or Vista on it that is. All you need to do is download the NEF Codec from here:
http://www.nikonimglib.com/nefcodec/index.html.en
and follow the instructions towards the bottom of the page. You will be able to view NEF files directly in a Windows environment without needing to install any other application, or need to uninstall anything afterwards.
Regards,
Duncan
PS, there are similar codecs avaiable for Canon and Pentax raw files to for others who don't use Nikon.