For the recipient to be able to view the presentation they must have either powerpoint program or the viewer. But what you can do is simply include these links with the presentation file so that they could easily download the free viewer/program if they cannot run your presentation file.
NeoOffice for Mac:
Hope this helps. Let me know if you have any questions.
It doesn't really matter you can send in either format, but the playable version is PPS, so I would send it as PPS, and the user can change to PPT by simply renaming the file which will make it editable.
Thanks for the accept. Let me know if you have any other questions.