Hi

You need to embed the fonts - office button -> powerpoint options -> save ->
embed fonts in the file. There are a few 'gotchas' with this however: only
truetype fonts can be embedded, not all truetype fonts can be embedded, and
you may have a file size explosion. For more details see here:
Embedding fonts
http://www.pptfaq.com/FAQ00076.htm

Other than that, be aware that smartart turns to images when a pptx is
opened in earlier versions of powerpoint or the viewer so you will lose
animations... Perhaps best to run the compatability checker or save as
97-2003 version so you can at least see what might happen...

Hope that helps,

Lucy