Preview:

In this tutorial I will show you how to make a Windows Vista Icon in Gimp.
This is the first time I use GIMP. so if I name a tool name wrong, sorry.
I was using GIMP 2.2 on Mac OS X during the tutorial.
Enjoy!

1. Go to File > New and create a new image 250 x 250px.

2. Create a new Layer, and with the Path Tool create something like this:

3. Click on "Create selection from path" in the path's tool options.

4. Now you will see the the design you made with the path tool is selected and dotted.

Change your colors to: #fff29e to ffd46f :

And with the Gradient Tool, drag it from the top of the folder to the bottom, this is how it should look:

5. Select the folder and go to Select > Grow - Grow by 1 Pixel.
Now go to Select > Border - Border Selection by 1 Pixel.
Change your color to: #fff4db, and with the Paint Bucket (Shift + B) Paint the border.
Now go to Select > None.

6. Select Again the folder. and go to Select Grow by 2 pixels.
Now go to Select > Border - Selection by 1 Pixel.
Change your color to: #f4c85b, and with the Paint Bucket (Shift + B) Pain the border.
Now go to Select > None, and should look like this:

7. Go to Layer > Layer Duplicate
Hide the first Layer: like this:

8. With your 2nd layer. Select the "Change Prespective Tool" (Shift + P) and do this:

9. Select the Scale Took (Shift + T) and Scale the image down to:

10. We are done with the folder, now we need to add the shadow.

11. Make a New Layer. Now with the "Select Elliptical Regions Tool" (E). Create a circle like this one:

12. Color the Circle in the new layer with whatever color you want (color will not affect the final result).
Now click Select > None.. You should have this:

13. Now on the Layers option, change the opacity to 0.0

14. Now go to Script-Fu > Shadow > Drop Shadow and Apply this Settings:

15. A New Layer called Drop Shadow will be made. Drag that Layer between Background and the First Layer:

16. Drag the Layer Shadow back of the folder, and you should get this:

Now you can add Papers, Music Notes, Movies inside the folder and make it for whatever you want. Enjoy!!