doPDF is a light weight PDF converter for windows. It installs itself as a virtual PDF Printer driver, after installing you can find it in your printers list.
To convert documents to PDF files select print from file menu and in the print dailog select doPDF as your printer. Conversion is quick and works well with out any quirks.
Remember this is not a PDF reader, it is just a writer so you need Adobe reader or some other PDF reader to open the created files.
PrimoOnline creates PDFs online, for this you need to give your email and wait until it arrives to your inbox. With doPDF you can have the convenience of creating pdfs anytime in just 2 clicks even when you are offline.
It is a freeware for Windows Vista, XP, 2008/2003/2000 Server (32 and 64-bit), file size is 1.4MB.