1. Right click on My Documents (in the Start menu or on the Desktop)
2. Choose Properties
3. Type in the secondary drive in the Target field. (eg. D: )
4. Click OK or Apply
5. Windows will ask you if you would like to move all of the documents from the old location to the new location.
6. Click Yes or No



NB - In effect the My Documents folder is only a shorcut to another location on your HDD. Regardless of whether you use the default My Documents or create a new one.