If you're looking for alternative PDF software, consider:

If you need the functionality that Acrobat X Standard provided (basic creation, editing, and merging), there are modern, safer, and cheaper alternatives:

Do not download Acrobat X Standard. Look at modern alternatives like PDF-XChange or the current subscription version of Adobe Acrobat.

If you have the original installation DVD, this is the most reliable way to reinstall the software on a compatible machine. Critical Installation Requirements

Alternatively, you can download Acrobat X Standard directly from Adobe's FTP site: