This is one approach to print files to PDF format without having to use a commercial
program such as Adobe Acrobat and its associated API.

The technique uses Ghostscript and Redirection Port Monitor - two free
programs for creating PDF documents provided free by Russell Lang.  

SETTING UP THE PDF PRINTER:
Here are detailed instructions for installing and configuring the virtual PDF printer - cribbed from:
< http://masterdev.dyndns.dk/know/freepdf.html >

1. Install Ghostscript to C:\
<http://www.ghostscript.com/doc/AFPL/index.htm>

2. Create a text file (c:\gs\pdfconf.txt) and add the following text:

-Ic:\gs\gs8.11\lib;c:\gs\fonts
-sDEVICE=pdfwrite
-dNOPAUSE
-dSAFER

Note that the first line points to version 8.11 of Ghostscript. If you have a different version or installed it to a different location, make the appropriate changes.

3. Download, unpack, and Install RedMon (Redirection PortMonitor)
<http://www.cs.wisc.edu/~ghost/redmon/index.htm>
* When you run setup.exe you will only see a message box.

4. Go to Printers/Faxes menu under the Start button in Windows and add a new printer.
* The driver for the printer must be for a /color postscript/ printer. I chose HP Color Laserjet 4550 PS
* Set the printer port to RPT1: (the redirected port)

5. Configure the port
Redirect Port to: "C:\gs\gs8.11\bin\gswin32c.exe"
(Update this line to reflect your version and location of Ghostscript, if different)

Arguments for this program are:
@c:\gs\pdfconf.txt -sOutputFile="%1" -c .setpdfwrite -f -

Output: "Prompt for filename"
Run: "Normal"

6. Try printing something in color to this printer. If everything works right, you will be prompted for a filename that the PDF file will be saved under (Don't forget to add the .PDF extension).