The difficulty is that the downloads are on 2 attributes and the CD on a 3rd ...

But, you need the 2 download attributes -- or -- the CD ... but not a combination on both ...

Because of this you would have to set up the Download attributes separate from the CD attribute and rely on the customer to actually select the Downloads as you cannot have them pre-set for the customer or they would get them with the CD ...

Is there a problem in offering this as:

Download 1
Download 2

Without CD
With CD

Where the customer always gets the Downloads? This might be able to work, but I have to test the shipping on it ...

Or, you could make these separate Products and use something like cross sell or X-Sell to help the customer find the matching product in either format ...