Hi,
Your Windows 7 machine may have PDF writer on it therefore you can print to pdf file. You have to install PDF writer on your Windows 8 machine. There are many of them including few free such as the following software:
http://en.pdf24.org/pdf-editor.jsp
After installing it, you can see more option(s) including print to pdf file(s). You can also use it to scan to pdf file too.
Regards.