Use the "Start" button.
Can you see "My Documents" or "Documents" as one of the choices? If not, right click on properties, go to "Start Menu." Click on "customize" - and scroll down until you see the "My Documents" option. Click to check it. Then close and redo the Start Menu.
In XP and Vista: Right click on "Documents" on the start menu. The window should include "Location" and show it (probably under your username on the C drive). Click the location. Browse to the new (D?) drive. If you have not done it, make a new directory on D called whatever ("My Documents" simplifies it by giving it the same name Windows will use for it.) Click on it.
Windows will now ask you if you want to move all your files to the new location. Say yes. This moves both files and other pointers (some may be related to your music or picture files).
In Windows 7 there's one extra step:
In place of right clicking on Documents from the Start Menu, left (regular) click on your name (should be at the top on the right side of the start menu). This will open up your username file area.
Now, find "My Documents" folder and right click on it.
As in Vista, there should be a tab that says "Location" (if you use a replacement from Windows Explorer file manager, you may need to turn that off - Directory Opus will not show the "Location" tab, but Windows own file manager does).
Again, browse to the new location, click and set it. As before, it should move all your files.
NOTE: In Windows 7 you can actually have several "Documents" locations at once. This is the new feature called "Libraries." You can read up on it, but it lets you have more one than major location for your documents, pictures, music, or whatever. It does not replace sub-folders, but gives you some additional flexibility.
DrTom