Does anyone know if the following is possible and if so what the best way of doing it is for free?
I am generating a PrintDocument in a project I am currently workin
You really should be looking at iTextSharp (it is mentioned on the iText.NET page recommended earlier)
http://itextsharp.sourceforge.net/
PrintDocument is meant for Windows Forms applications but is up and coming in SilverLight, see this video... http://silverlight.net/learn/videos/all/printing-api-basics/
If you wish to continue with the PrintDocument and a web application, I think SilverLight 4 (which is beta right now) is the only way to go, or your going to have to have a lite weight windows form application installed locally for the end user that maybe uses web services.
iTextSharp is a great tool for generating PDFs with .NET on the Internet. I highly recommend it; I've used iText with Java...and have been using iTextSharp for the past few years.