I would recomment avoiding all D&D games (except for Neverwinter Nights). 90% of them were terrible at porting the paper and pencil version to pixels (try saying that five times fast).
If you want to play RPG's on a computer, I wholeheartedly recommend the Might & Magic series - not the Heroes games, but the actual RPG's - well, not IX. IX was bad. V and VI are actually one game when combined and will provide you w/ about 150+ hours of entertainment.
Of course, you could play the ultimate RPG: Wizardry 8. It is hands down the best in the genre. It was designed as a CRPG that was supposed to play like a paper and pencil game.
If you're on consoles (mostly PS1 and PS2) I would recommend the Final Fantasy series (duh), but also the Wild Arms series. They're kinda' like Final Fantasy meets the old west. Seriously good fun.
-Ferret
"Avoid the Tales of XXXX series - they're bad"