I bought TDU on a recommendation that said the mega pack was a "must have". I wasn't too happy when I discovered it wasn't available although it still has a catalog listing. Considering it was a download I was especially miffed because it isn't like Atari would have to order disks, cases, printed art work and have it eat shelf space. At the very least they could have offered it to places like direct2drive, GOG, Amazon or any of the places that sell software downloads. TDU is still readily available at a number of places which makes the unavailability of the Mega Pack even more frustrating.
As to being 3 years old, I just re-purchased Freespace 2, Planescape: Torment, Red Baron and Red Baron 3D all updated and working fine with my Windows 7 64 bit machine. What are those games? Going on 10 years old?