The way the Components dialog box works is that it actually looks inside a folder to see if any files there it can display.

To get a better picture, here is what you have to do in a Windows computer:

Computer>Hard drive(or where SU was installed)>Google> Google sketch up [your version]>Components

Thats where SU stores its components, if you want an extra pack look at the guy above or wait until Google makes a v7. Personally I just put any models that I like into this folder.

Some of you might not know is that now the dialog box actually links to the 3-D warehouse, so whatever you search in that search box there will come up the same in the warehouse dialog box. Simply its just a faster way to surf the warehouse without taking up so much space when you don't want it to.
Yea its messed I know.

Open the Model - SKP file.
Open the Materials Browser window.
Pick the Model tab [little house symbol]
Click on the icon of the Material you want to extract.
Right-click context-menu gives you options - Save_As...
Save as a SKM file with its name - into the Materials folder - I suggest you make a sub-folder for these extracted materials so they are easy to find and manage later on...
That Material is now saved as a SUp SKM format file that you can access in any other Model, through the Materials Browser by navigating to the appropriate sub-folder in the Materials folder collection...

Repeat this for any Material you want to extract from the Model.

You can extract materials from any model and save them in this way as SKM files so that they are re-usable in any other model...

If you had picked 'Export Texture Image' instead of 'Save_As' then you wouldn't have got a SKM file saved, you'd get a JPG or PNG file - i.e. the image that the material uses as a texture, extracted back into its original form. There is a Ruby script [fast_tw.rb] that will extract all of a model's texture-images into the model's folder - unfortunately there is no equivalent to bulk extract SKMs. The SKM file is a sort of zip file containing the image, its thumbnail and 3 other xlm documents giving colour data etc... To see this, copy a .SKM to your desktop and change its suffix to .ZIP, now open it in your ZIP-application and you'll see the contents listed. No one has yet worked out how to auto-write all of the model's SKMs out of SUp with Ruby... it will happen. Using pop-out 'Save Library As...' lets you bulk export ALL of the model's SKMs into a new folder...

It might not have been 40 for the stones, but it was considerably more than 10 for each of the textures. and I downloaded this with the standard free SU 5 or 6 and then had to download the components packs separately,

I know when I used to go into the textures it was enough textures for each surface to have to scroll down the choices with the scrollbar, and you certainly do not have to scroll down anything with only 10 choices

That would install it into SU 6 (as it says). Just install it into
F:\Program Files\Google\Google SketchUp 7 - if you have Program files installed on the F drive (normally this would be the C) it will find the Components folder inside automatically.