I think that pdftk will also convert a PDF to version 1.4. pdftk is apparently available for Windows, Linux, Mac OS X, FreeBSD and Solaris.
To convert files, all you seem to need to do is:
pdftk mygoogle.pdf cat output converted.pdf
is the file from google, and converted.pdf
is a name for the output file after conversion.
I live in the UK and can't seem to get access to the PDF pointed to by Arunava (as seems to be the case with a number of google books) so I can't test this particular file.