Well, the standard icon for a hard drive is shell32.dll icon number 8 on my system (Windows XP Pro), and I checked it by using that information in the Drive Icon Changer program, and got the result that you saw in the screen shot that I posted.
Short description of how to find out an icon's number:-
Right-click any shortcut and choose Properties. Click the Change Icon button. Type the path (eg C:\Windows\System32\shell32.dll) to the file that contains the icon you want, or use the Browse button to select it from its folder location. When you see the icons displayed in the Change Icon dialog box, count--starting from zero (the number of the first icon in any file)--from top to bottom, left to right. When you get the right number, click Cancel twice
Description with pictures...
1. Create a shortcut (eg on your desktop). It can be to any location or program. Right click and choose "Properties".
2. Click the Change Icon button. Then click the Browse button in the Change icon dialog and navigate to C:\Windows\System32\shell32.dll
3. In this picture icon no. 8 is highlighted, counting from 0 at the top left, going down in columns. The top row of icons are numbers 0, 4, 8,12,16 and so on.
4. When you are satisfied you can cancel your way back out of everything and delete the shortcut, or you can practice assigning various icons to your temporary test shortcut. You could also try assigning different icon numbers to your local hard drive with the Drive Icon Changer program, to satisfy yourself (a) that it is possible, (b) that the numbers are as I said.
