Looks like it's me to the rescue...
1)First, get VPView from
http://www.descent-freespace.com2)Next, install it.
3)Using VPView, browse to your Freespace 1 directory, then to the "Data" folder, then open "Freespace.vp"
4)On the left side of your screen you should see the various directories in the file. Click "Interface", then scroll down until you see CrIm01.PCX
5)Depending on the version you got, you may or may not see a preview of the picture in the lower-left corner. If it satisfies you, then just go through the rest of the CrIm##.PCX pictures.
6)If you want to get all the credits images out of the VP, click "Crim01.PCX", scroll down to "CrIm55.PCX", hold shift and click on it.
7)Then hit "Extract to Dir" and select a directory of your choice.
8)Open the PCX files using your favorite view (Paint, IrfanView, whatever)