I often use AbiWord for word processing, since it has a better UI than OpenOffice. Considering that there's also a standalone spreadsheet - gnumeric, is there a standalone presentation editor/viewer in the vein of PowerPoint or Impress?
Only installing Impress seems wasteful since I have to install much of the OpenOffice backend as well. PowerPoint Viewer is fine unless I find I need to edit a slide - I'm aware of these alternatives.
Portable, or low-dependency software would be preferred. The question is primarily for Windows systems (though I'd upvote any good Linux-based answers), and compatability with at least classic Office PowerPoint slides would be essential.