PDF Bundle is a free portable tool which lets you attach any file to a PDF document quickly. You can also attach other documents inside PDF, such as, Microsoft Word, Excel, Visio, or Publisher documents. It does not require any installation, just download it from the link mentioned in the end of the post and run the executable file.
To attach any file to a PDF document, specify the Source PDF, the File to attach, the page at which you want to attach (Attach to page), Attachment Title and Attachment Author. Once you have filled all the required fields, click Bundle Now and your specified file will be attached to the source PDF file.
It works flawlessly on all versions of Windows including the latest Windows 7. Enjoy!