I use a freeware called 'PDFcreator'. It acts like a printer driver - so when you go to print anything, seled PDFcreator instead of your printer.

Then instead of printing, it brings up a dialog where you enter keywords and such if you want to, click save - and then it brings up a dialog asking where you want the PDF stored.

Here's where you can get your copy:

http://sourceforge.net/projects/pdfcreator/