What can I say? If there is one game you have to play, then I'd say it would have to be Baldur's Gate 2.
Great storytelling game, with an awesome and massive history and universe to play in.
The game itself has god knows how many hours worth of game play. Plus you may even play it a few times (I completed it 5-6 times myself). Impressive towns and areas to visit, hundreds of quests to complete, plus the main plot is utterly intriguing and absorbing.
Truly involving character development, and even party development. Amazing, and perfect game.
I've done a bit of research and you can get a mod kit called 'BGT' or Baldur's Gate Trilogy. Search for Spellhold Studios and BGT in Google (I can't seem to link it).
What this does is combines the two games plus both expansions into one game in the BG2 engine. With several fixes and tweaks by default. Note that due to the passing of time from BG1 to BG2 there are certain facts that cannot be avoided. Some characters will change. You can only really count on your own BG character carrying on in BG2.
Also make sure you search for the 'Widescreen Mod'. When you run this over the top of the BGT installation you can select your native resolution.
I am playing the trilogy in 1920*1200 full screen on a 27' monitor and the game looks absolutely stunning! You can't beat hand drawn pre rendered art. Well I think so anyway. Give it a go, especially since the Baldur's Gate Compilation is sold as a single pack for about 10 quid on play.com.
You might want to also get some AI scripts to assign to your characters to make them a bit smarter. The default ones are very basic, depends how you want to play really. For complex fights I turn the AI off completely.