no no, Prima guides are notorious for being full of errors and false information.
Did Prima do the NWN guide, or was that Versus? I'm thinking the latter, but boy was that thing a piece of garbage. The horrible "jokes," lots of incorrect information, and plenty of typos (like a +21 sword). Plus, since they wanted it to be ready in time for the game's release, they published it while the game was still in development. They didn't even know how the game ended! I think it said something like "Step through the portal and...we're not quite sure what happens next."
I'm pretty sure Prima did a BG guide. I remember it vaguely, cause I didn't own that guide. I remember quest info being little more than a few blurbs. Much of it was devoted to a "journal" detailing a characters in-game adventures. Ironically, Khalid survived the quest, but Imoen died in the Cloakwood Mines.
That being said, I havent bought a strategy guide in quite some time. In fact I think it may have been NWN. There's walkthroughs on the internet, wikis, forums. Plus, I do like to find out a lot of things on my own.