I still own the massive dungeon book that came with the CD-ROM. It has the maps of every floor and foes you'll find along the way.
One of my favorite parts of the entire dungeon crawl was the mysterious sibilant voice of a merchant, Preybelish, behind a door on one of the dungeon floors in the dwarven mine. A small slot in the door was used to speak and pass items/gold back and forth from. The room was shrouded in magical darkness so you couldn't see in. Later you have the opportunity to fight the merchant and low and behold it's a dark naga.
Even with the guide, that always struck me as the best part of D&D, the plot twist that the person you may be helping is in fact a bad guy. The "deal with the devil" so to speak can sometimes be very rewarding if your willing to pay the price later.
Anyways the CD-ROM no longer works on my current system. Please bring this to GOG.com. You already have Icewind Dale, Baldur's Gate, Temple of Elemental Evil, Neverwinter Nights 2 and all the older games like Secret of the Silver Blades, Curse of the Azure Bonds and Pool of Radiance.
This is the ultimate dungeon crawl successor to those, though Neverwinter Nights 2 is actually the successor to this game being the first ever to implement the 3.5 edition.
What I am saying is, I already own all those via GoG.com. All but Pool of Radiance Ruins of Myth Drannor. Help me complete my collection.