How can I turn my Powerpoint presentation into a secure PDF?

Hmmm... that is a bit odd, now that you mention it. If you're pitching a client on your services, there's little reason why they would want to disseminate your pitch to the rest of the company unless it's some sort of üaut;ber-egalitarian firm, and few really are, once you look closely. I think you're right to be a bit curious and to take some steps to control how widely that information can be disseminated.

As you know, Adobe's PDF documents are a great choice, and give you lots of control over what the recipient can do with the information in a way that's portable across both the Mac and Windows. Heck, even the nerds in IT can read it even though they're running Linux-based netbooks. :-)

To get a PDF from Microsoft PowerPoint, however, is a bit of a trick because while PowerPoint can save your presentation in a lot of different formats, as you can see here:

what it can't do is save your presentation as a PDF. That's kinda dumb, but I am guessing that it's a technology licensing issue more than anything else.

Instead you need to use the print to PDF feature of Mac OS X that's one of its killer capabilities. And it's easy too... just choose "File" --> "Print":

Once you get to the print dialog window, however, don't choose "Okay" but instead click on the "PDF" button on the lower left corner:

As you can see, there are lots of interesting things you can do here, but we'll just choose "Save As PDF...", which brings us here:

If you just want to send a regular PDF without any constraints, this is far enough: give it a good name, click "Save" and you're done.

Since you want to add some security features, however, click on "Security Options":

For the document I was saving as I did this process, I didn't want to have a password to prevent it being opened, but instead one that made it difficult to copy or print, just as you seek. Here's how I configured that:

Finally, at this point, I clicked on "OK" then "Save" on the print window that I returned to, and got to watch PowerPoint work on the problem...

Not more than a few seconds later I'm done and the document is created and ready to disseminate.

To test it, I opened it up in Preview and tried to print it:

Exactly as I would hope, and exactly what you need too.

Good luck with that client, too!