Windows is actually a DOS program. DOS is not an Operating System either. It's a program loader. Very popular on the net. A postscript file can have all sorts of nifty doo-dads in it, things like pictures, font changes, italics, etc.
Text files in .ps are invariably MUCH better looking than their ascii counterparts.
The primary or default directory. Saying a file is in your root directory will be understood by all to mean that the file is to be found in the lowest level of your directory structure. Some .sig's are interminably long and very annoying. This might seem a bit odd at first. If you tilt your head to the left about 90 you may see a smiley face.