Best adaptation? I'd have to go with Neverwinter Nights II. The system is the truest to 3.5e D&D as I have ever seen, and it helps that the graphics are absolutely stunning -- particularly the landscapes. The only downside is that creating modules is an extremely time consuming task. Fortunately, there are a lot of talented folks out there creating modules you and your friends can play; not to mention the original included campaign, which was very well done, I might add!