Whether you use Netscape Navigator™ or Internet Explorer™, you will have a pull down preference window (Mac) or properties window (Windows 95-2000) that you can access within you browser. Below is the Netscape Navigator™ preference window for Mac. It is similar to the ones from Internet Explorer™ for Mac and Windows 95-2000. Locate the subheading for helper applications. Somewhere on this list will be a setting for Portable Document Format (PDF). Click on the "edit" settings button:
What has happened is that your browser's default is set to handle PDF files by copying them to your desktop and then launching Acrobat Reader to view them. This means that you have to jump between Acrobat and your browser program to view multiple pages.
When you install Acrobat Reader, it should ask you to install a plugin in your browser's plugin folder. By changing your browser to handle PDF files using this plugin, it will allow you to view PDF files within your browser just like you do photos, video and audio files.
Now all you have to do when done viewing a current PDF page is hit the back button of your browser to get back to the index and go on to the next page.