[Splines]

There are back-compat features in Word to render files using old rules, so work has been done to help preserve your visual layout across versions.

That said, there's a ton of churn between different versions of Word, so there's no guarantee a bug-fix (or sadly, a regression) won't cause your document to display differently anyway.

FWIW, Word has PDF/XPS export built in as well. (I believe Word 2010 has it in the box, and Word 2007 has some silly downloadable component to enable this).

[drinian]

And, of course, with the free PDFCreator virtual printer on Windows, or the PDF generation builtins on Linux and OS X, there's no reason you can't use PDF from any app...

Not to mention that PDF generation was probably added to word as a response to OO's capability.