coper210 :
Did the product key work after you did a clean install?
Your product key will work fine if you install W7 on a new drive, just activate it when you finish. The way it wokrs is it can only be active in one place at time, so it when you activate it on your SSD, the copy on your old drive will be 'deactivated'.
To answer your OP though - Id definitely clean install. Its a lot nicer to a new drive to start from scratch, you get the nice feeling of it being totally clean haha. Ive found cloning can sometimes cause issues when you try and to an access somethings (corrupt installations etc) so it'd might save you some hassle.
What I ended up doing in your position was doing a clean install of W7 but copied over files that I wanted from my old HDD - then wiped the HDD and used it for data storage.