DriveThruRPG/RPGNow has classic D&D PDFs available again on a new site, DNDClassics. There are about 80 items available now (from all versions of DnD through 3.x) and more will be added each month. However, if you purchased D&D PDFs from DriveThruRPG/RPGNow before WOTC pulled them a few years ago, you will be able to download the newly updated D&D PDFs for free in the My Library section of the My Account page as they are re-released by WotC. You can log in with your DriveThruRPG/RPGNow account. More later.