Anyone who has fond memories of D&D from the 70's, 80's and early 90's MUST play the entire Baldur's Gate series.
You'll see some folks here and there complaining that the graphics are 'dated'. Ok, fair assessment (now, in 2011.) 2D games are pretty much done and gone...no one does brilliant hand painting of environment backgrounds anymore.
But, do you want character interaction? Depth of story? Do you want to care about your cohorts and the innocents that need to be saved? NO game I have played (except maybe KOTOR I, Fallout 1, 2, 3, and New Vegas, Mass Effect 1 & 2, Dragon Age 1 & 2, and the Witcher...ok, so that's a few :) ) has remotely been able to capture the depth and goodness of roleplay that is Baldur's Gate. (Addendum) Having named quite a few games that can 'hang' with Baldur's Gate, please note that *most* of these were created by Bioware (the creator of Baldur's Gate.) However, if you are a D&D afficianado and you haven't played Baldur's Gate...OMG...there is no substitute for Baldur's Gate...NONE...even now in March, 2011. (Neverwinter Nights 1 is a disappointment and NN2 has a thoroughly nihilist/masochistic ending beyond your control, plus much of the UI look and feel is all wrong. DDO has its high points, but it's still a MMORPG with an excessive Middle-eastern flair that serves MIILK and no alcohol in the taverns... I'm not making this up.)
If you've never played Baldur's, but you're totally sold now and are ready to get it...get it. Then, download the Baldur's Gate Tutu (free project online.) It converts all of the first part (Baldur's Gate) to use the Baldur's Gate II engine (better resolutions) You can start at level 1 in Baldur's Gate and take him or her all the way to level 40 (or more) in Throne of Bhaal.
According to the games I've tagged in Gamespot, I have over 114 PC games I own/have played (I haven't tagged them all yet); Baldur's Gate is *still* my favorite game of all time.
I could go on and on, but I don't want to ruin any of it for you. Play it...and tell Minsc and Boo that I sent you. It's an epic adventure you'll never forget.