Virtual PDF printers are actually virtual drivers which install on your system and provide you with the option to print your documents to a PDF document as opposed to using physical paper. They are overall rather easy to use and involved selecting the printer to use from within the "Print" dialog.
You can use virtual PDF drivers with virtually any Windows program that has a print function. The most popular program today would probably be Microsoft Word or Microsoft Excel.
Many of these programs are Shareware (not recommended) and some of the best are actually freeware. Take your pick!
Create PDF files from virtually any type of text or image document with conversion tools supporting drag and drop DOC to PDF.
PrimoPDF is software which can install a virtual PDF printer.
A virtual printer, PDF creation application.
PDF Creator is software which can install a virtual PDF printer.
PDF Printer Driver, PDF Creator, PDF Writer.
eDocPrinter PDF Pro is software which can install a virtual PDF printer.
Easy Document Conversion to Adobe PDF from any application that can print.
Print2PDF is software which can install a virtual PDF printer.