I was never into Star Wars that much either, but I do have to say KOTR does have a great storyline. Bioware has made some great games with storylines, look into Jade Empire as well.

I have to echo FallOut 1&2 and Planescape:Torment, 3 great games with some great stories, and some of the greatest characters. It was a shame when Black Isle Studios shutdown.

There is an old school courtroom/crime game, made back in 1997, that fits the bill on what you are looking for.

Its called DA: Pursuit of Justice, not only do you gather evidence, but you plan your case out, interrogate witnesses, and then
actually play the whole trial out in the courtroom. You can object/substain based on false information witnesses testitfy..etc It really was a great game back in the day, ran flawlessly on windows 95, and I have read that it will work on xp as well (in win95 compatibility mode).

There are 3 games in DA: Pursuit of Justice

Case 1: Sunset Bolevard Deuce

Case 2: The Gastsby Diamond Jewelry Thief

and Case 3: The Rat Tattoo Murder

each game is sold separately, or there is a 3 case combination pack that used to be available.

here is a link to case 3 to get you started, if interested:

http://www.cdaccess.com/html/pc/pursuit.htm

Good Luck

Absolutely Planescape: Torment

Great story, facinating characters (gotta love Morte), and some unique gameplay elements.

FallOut 1 & 2 comes a close second to it though.

The Fallout Series definately.

Also look into getting Planescape:Torment, great dialog, good storyline, fun combat.

As with everyone else, I would say definately Unreal Tournament 3.

Also if you enjoyed playing Crysis and haven't played FarCry, check for it in the bargain bins. Its made by the same developer, and even offers better enemy AI. The multiplayer isn't too shabby as well, decent community of players.

As far as RPG's go, if you haven't given them a try yet, pick up Fallout 1&2. Again, you'll find them cheap in the bargain bins. Both of them are great RPG's and will give you some background on the Fallout world, so you'll be ready to play Fallout 3, when it comes out, late 2008/early 2009.