This is, definitely, not a hack for Google to detest this post. This will teach you how to copy and retrieve the files that Books.Google.Com temporarily saved in your computer before showing it to you through web browser.
follow the steps bellow:
1. Open your Web Explorer (Not Firefox). Make positive that you are the admin of your computer. Then, go to the page in books.google.com that you need to download.
2. Now, go to “C:\Documents and Settings\%your admin name%\Local Settings\Temporary Web Files\” of your computer. Delete all of the content of that folder.
3. In your Web Explorer, refresh the page and browse-thru the pages of the books that you need to download.
4. Refresh the “Temporary Web Files” folder. Copy all PNG files to another folder. You can distinguish PNG Files through its icon.
These files that you have copied are, actually, the pages of the books that you have browsed.