• Go into Windows Explorer on the Desktop.
• Go to http://picasa.google.com/ and click on the blue Download Picasa button.
• Click Run to immediately start installing Picasa or download it to install later.
• When Picasa starts tell the first screen to scan your My Pictures folder.
• Tell the photo viewer to not run (it will be enabled later).
• Go to the Tools menu -> Folder Manager and set the folders to be scanned.
• After Picasa is installed, if you want a desktop shortcut:
• Go to the Start screen and type picasa3.
• Right-click on the Picasa3 Icon.
• Go to the bottom of the screen and select "Open File Location".
• Right-click on the Picasa3 program and select "Send To" then "Desktop (create shortcut)"

If you have videos or movies in your collection you may need to install video codecs, Picasa doesn't have a lot of video support built in.

The following steps check for installed Video Codecs then add any Missing video codecs to your computer so Picasa will recognize video formats. 

First check the Movie settings:

• Go to Tools menu -> Options-> File Types tab. at the bottom of the file types list there are 2 boxes called movies, and QuickTime.
• Both boxes need to be checked and they shouldn't be greyed out (unselectable).
• If they were unchecked, check them and click Ok on the options box.
• Exit Picasa and start it again and see if the desired Video format now works.

  If the settings were greyed out or importing still didn't work, the next thing to do is install or reinstall your video codecs:

Installing Video Codecs:

Quicktime Codec

Apple Video formats like .MOV and some MP4 formats are supported by the QuickTime codec.

• Install the Apple QuickTime package from http://www.apple.com/quicktime/download
• ( If you do not want Apple QuickTime loaded on your computer,
  Install  QT-Lite http://www.filehippo.com/download_quicktime_alternative/ 
  (QT-Lite will give you the codecs without the Apple bloat)

 K-Lite Codec Pack

Most video formats not supported by QuickTime are supported by the K-Lite codec pack.
If you have other types of video files you might want to try installing the K-Lite Codec Pack.

• Install the K-Lite codec pack from: http://www.filehippo.com/download_klite_codec_pack/
• If your windows 7 is 64 bit, also install the 64 bit version of K-Lite from:
  http://codecguide.com/klcp_64bit.htm  in addition to the regular 32 bit version.

 After installing the codecs you may have to go to Check Movie Settings again and check the video types.

Windows 8 hijacked the Photo Viewer settings and has it's photo viewer set up as the default viewer for all photos.

In Windows 8 the photo viewer must be configured using the windows tools as follows:

 

If you want to make PPV your default do the following:

• Go to the start screen. (If you are in desktop view, mouse down to the lower left corner and click on the start screen when it appears.)
• Type the word "Default" on the keyboard.
• Select the tile "Default Programs" in the Start Screen in the upper left.
• In the default programs screen select the top option "Set your Default Programs"
• In the Programs list box, scroll down and select "Picasa Photo Viewer"
• In the Lower right side select either Set as Default, or Click Choose Defaults and choose the file types you want it to open.
• Click Ok. 

Note: Be aware that Picasa Photo Viewer will now be the viewer instead of "Photos" on the Windows 8 start screen.