I had a similar issue in selling software as a download along with supporting hardware that is shipped manually world wide and looked at various shopping carts in the hope of finding one that would allow people to puchase both in the one transaction. In my case I needed to have:
1) software available as an imediate download via a protected link - also available on CD + download
2) have the purchaser's unique licence generated on the fly and included in their welcome email
3) have all the purchaser's details added to a MySql database on my server
4) hardware items added to the same cart so that the purchase could be made in the one transaction.
Initially I too, had two sections to my shop - and used Download Guard for software delivery. But people found it both annoying and confusing in having to make two separate purchase transactions.
*REMOVED SOFTWARE NAME* - together with some additional modules, provides all these features, together with many more, but I'll mention just a couple such as:
1) ability to recognise the purchaser's location via IP address and change the currency displayed in the shop accordingly
2) ability for EU based vat registered businesses to add their registration number and avoid paying the UK tax.
Coffeecup's cart is really a very basic one - in addition to not being able to handle downloads, it cannot even track the purchasers' details and relies simply upon the Paypal purchase notification; something I find amazing. But my comments are not intended as a criticism; indeed the overall simplicity can be a benefit in many cases - the company seems to specifically target its products at people looking for easy to use software. So I think it best to just accept that fact. And then just use it whenever it is appropriate.
For example, I bought Shopping Cart Pro (and Designer Pro) as a simple cart solution for a client selling fine art prints online and for this it works well; the (non vat registered) client is delighted with the shop, which thanks to Designer Pro, I was able to make match the overall web site design quite well. In this case, something like Prestashop would have been "way over the top" for the cart section of his site.
People do seem to want software downloads immediately after purchase, so hopefully the CC team will update their cart to accomodate digital downloads soon.
Peter