Imagecache_Profiles module allows you to set user profile pictures that are consistent throughout your site and allows avatars on the user profile pages to be a different size. 

- Download and enable the ImageCache module
  - create a new ImageCache preset with the following settings
    - preset namespace: user_image_default
      - select "scale" from the add a new selection drop down menu
        - set width and height to 100
        - set scale to fit to Outside dimensions
        - set weight to 0
        - update preset
      - select "crop" from the add a new selection drop down menu
        - set width and height to 100
        - set x offset and y offset to center
        - set weight to 1
        - update preset
    - preset namespace: user_image_large
      - select "scale" from the add a new selection drop down menu
        - set width and height to 200
        - set scale to fit to Outside dimensions
        - set weight to 0
        - update preset
      - select "crop" from the add a new selection drop down menu
        - set width and height to 200
        - set x offset and y offset to center
        - set weight to 1
        - update preset

- Download and enable the ImageCache_Profiles module as usual
  - Enable user pictures at admin/user/settings
    - set picture maximum dimensions to 1600x1400
    - set picture maximum file size to 1024
    - set your picture guidelines text to: “Photo must be larger than 100x100 pixels.”
    - select the ImageCache preset to set the user picture size on a user's profile page
    - select the ImageCache preset to set the default user picture size throughout the site
    - set picture minimum width in pixels: 200
    - set picture minimum height in pixels: 200
    - save configuration