I’m currently using the Screen grab extension in Firefox to save complete websites as pdf files to read them later or print them eventually. Screen grab has some limitations, mainly size of the website that should be saved and that it only works in Firefox. I sometimes use Opera or want to convert other documents such as emails to pdf.
DoPDF looks like the perfect replacement for Screen Grab. It is a freeware application for Windows and takes only a few megabytes of hard drive space. It adds a virtual printer to your installed printers in Windows and you can choose to make it the default one. Please make sure that the Print Spooler service is running during installation, otherwise the setup of the virtual printer will fail.