I can't remember exactly how I did this but I have mine setup so that none of my folders like My Documents my music and my videos are on my ssd and so when ever I download anything or save a document file they are saved automatically on a seperate HD , I will have to try to remember what I did to change this and I will post back.
Edit
I think that I followed the directions on here, it was so long ago ) but this will work also
User Folders - Change Default Location - Windows 7 Forums