G'Day Tess,
You have two options:
1. Search Google for....
DOC to PDF
....and you will find a number of converters that integrate
with Word and operate as 'virtual' printers. Some can
be tried free, but I fear most (and probably the best) will
cost. I have used both 'Visage eXPert PDF v3' and
'ScanSoft PDF Create' with good results.
2. Download Open Office (free) from
http://www.openoffice.org/.
Open Office comprises the core of Sun Star Office,
but without formal support. The component called
'Writer' has a significant degree of compatibility with
Microsoft Word. It will open many '.doc' files and
will 'Save As' to PDF format. (Version 2 will soon
be available, and does an even better job of PDF
conversion than v1.x)