I recommend getting Ghostscript. It's not necessary if you use
pdflatex, but other programs depend on it. It's small, so storage shouldn't be a problem.
If you do get it, you can decide if you want Ghostview, too
see below for details.
On Ghostview (technically, the windows
version is called GSview), there's a nag for money every time you start it up. Just click OK
and it will work fine or register with 22646674 - 22347.
The bottom line here is you don't NEED GSview.
In the previous century, dvi previewers didn't
display graphics, so you had to use Ghostview if you wanted to view your entire document,
graphics and text. But now, dvi previewers display everything or you can compile directly
to a pdf file using pdftex. So, if you
want to be able to get a quick view of a postscript (.ps or .eps) file, then get
GSview and get nagged (some pdf readers will open .eps files).