Obtain latest source files
The very best way to get the latest version of PDO is to use a Subversion client and grab the files from this repository. The URL of the repository is: https://pdo.svn.sourceforge.net/svnroot/pdo/trunk and the files can be retrieved anonymously. Sourceforge has project-specific information on how to obtain, install, and use Subversion clients. You can also browse the source and the latest differential changes directly on line with the Sourceforge Subversion browser
Packages
Sometimes the source files will be packaged in a compressed format such as .zip, .gzip, .7z, or .rar. All such packages will be located at the Sourceforge PDO file repository. Generally the source files via Subversion are more recent, although hopefully they'll be the same.