Hmmmm,...good times, good times...
Exwitless is right that I used to play D&D. I also used to DM at conventions and was the Gaming Director for a very large local club here back in the day. I was also a Referee (the non-D&D term for a Dungeon Master) for many other pnp games in the club, at conventions, and at private meet-ups. Twightlight 2000 was one of my favorites. When I became one of the borg, I threw out about $600 worth of pnp materials and books, a fact that I was proud of at the time and which makes me sick now because almost all of it is irreplaceable...but I digress.
She is also right that Neverwinter Nights is a type of D&D game. In fact, it is currently the official AD&D computer game series from Wizards of the Coast, the people who bought the original rights to AD&D from TSR. Neverwinter Nights and the 2 expansion packs are excellent, but just like the original pen and paper games, (and this is the important part), they are frameworks of rules meant to be added to by the players. Just like in the pnp version, the computer verison uses modules - the D&D name for the story in which you are currently adventuring. These modules can be played by yourself or in groups (private or entire internet welcome). There are also persistant world servers for the mmorpg experience. The Neverwinter series has a huge fan base, and just like in the old school pnp games, many, many of the player made modules are just as good as, or better than the official, company made modules. Citadel of Blood for Neverwinternights comes to mind. I haven't played that one in a long time, but it was very good - and fan made. Google Neverwinter Nights and The Vault at the same time and you can get pointed in the right direction for a storehouse of user made modules.
What this means is that - just like with the pnp version - the game never ends until you want it to. You just pop your saved-out character into a different module and continue on. I have no doubt that if you downloaded and played every single current fan made module for Neverwinter Nights, you could play 24/7 for years on end and still not be done. Oh, did I mention that they are free? WotC has company-produced, low priced modules for download as well. NWN doesn't have too stringent of computer hardware requirements, but each expansion added slightly to the need for power. I probably won't buy NWN2 because I doubt my laptop will run it.
I didn't care for the Baldur's Gate series, but I think that is only because I already had NWN, and the graphics in that beats the snot out of BG. Since I already had NWN and no lack of new modules, there's not much reason to play the older ones. Especially when the fans recreate the old pnp modules and computer games in the new NWN modules (and do a good job of it to).
As far as non-D&D rpgs, Diablo 2 (with expansion pack) from Blizzard is a fun romp from a few years past. It might be hard to argue that it is a true rpg, but it has the fantasy elements, decent character development system, and is easy to pick up on. Computer requirements a pretty low and the boxed set can be had for cheap. I wouldn't bother with Diablo 1 - there's a reason they put out Diablo 2. Also, the expansion pack is just about mandatory if you want the game to be fun. I could go into why if you need me to do so. Like NWN, Diablo 2 is single player or networkable with both private, public, and official (Battlenet) servers. Our yong son and I currently play this game together networked in the house and it is a lot of fun.
Game on,
LDB