Here are my tips for persistent world servers to play at once you get the game:
http://www.xfire.com/clans/superfly2000/

I have Diamond Edition and I can say that this is the biggest bargain you'll ever get in a RPG game.

Diamond includes the original game, both expansions, the bonus module Kingmaker, the toolset with which you can create your own modules and the standalone server so you can put your module online in multiplayer mode for others to enjoy.

Note that putting your module online does require some knowledge of how to give your computer a static IP address and how to configure your modem/router and firewall to allow incoming requests.

You're getting not one game but 4 games (the original campaign plus the two expansions plus Kingmaker) plus you can download single-player modules made by other players plus you have many online games to choose from, plus you have the option of making your own games using the NWN structure. That's a value which is hard to beat!
Definitely yes. If you explore everything and do every possible mission in the original campaign, you'll be playing it for weeks before reaching the end. It's possible to complete the campaign in far less time, but it's to your advantage to do every mission and get the bonus XP to level up as far as possible. Besides, it's fun! :-)

Oh, and in case your disinterest in online play is due to fear of paying through the nose for online play, here's the best-kept secret WoW doesn't want you to know... online play with NWN is free!

NWN is a great game -- to play online.

The original campaign is pretty weak, but the expansions fare a little bit better. However, the bulk of this game's value is in its modding community (8 years worth of mods are available on nwvault.ign.com) and its online play. If you're a roleplayer, it's worth noting that there are actually more people still RPing on the first NWN than on its sequel: NWN2. I spent YEARS roleplaying on this game, and I can definitely recommend it to those of you who enjoy that sort of activity.

I probably don't have to mention this, since if you're on GOG.com you probably don't care about graphics, but the game's visuals are pretty dated -- even for its time. You get over it pretty quick, though.

NWN single player is the absolute most boring and lifeless game I have EVER played, and I've fallen asleep playing trucking simulators. Even the music is boring.

Your lack of interest in multiplayer may not apply here, as only some of the persistent servers have the flavor of what we think of as online multiplayer. On the more sophisticated worlds much care is taken to present an experience appropriate to a good singleplayer game. Good dialogue, long quests, strict rules of conduct, but not necessarily roleplaying. When I played last there were casual servers with rich world designs and a lot of content. (In fact, I wasn't going to buy this release, but thinking about those servers has changed my mind.)

I did it. Ubuntu 10.04 w/Nvidia 8600 (Nvidia driver, of course). Also done on PCLinuxOS (but that was about 3 years ago), but the HD crashed. (Stupid Maxtor!) Lost all of my good mods and characters.

While I'd agree that the initial campaign starts poorly (it was a shadow of what was planned due to Bioware being embroiled in a lawsuit with Interplay and losing the BG franchise) it does improve after leaving the city and has some nice sidequests (like deciding the "best" course of action in Charnwood). The campaigns included with the expansions are better but shorter.

Taste is a personal thing, but describing NWN single-player as the "most boring" is really overdoing it, even for a truck simulator expert. ;)

I was just about to buy this from Ebay, glad I didn't...... Gog is awesome!

Well the PLAN was to do it, without windows at ALL, and set up a nice guide to do it.

But, um, I sort of... went to Tampere and got drunk instead.

(:

Nonetheless, the PLAN is to write a nice guide and support it for everyone who wants to continue to play this, no matter what os they have.

You'll have to pardon my inability to resist hanging out with friends and having a few beers. After that's done, I'll return to getting the guide done.

I have, so far, got the package unpacked without using Windows. (knoppix CD, and wine.)

More info for you (or those of you using a 64bit version of Ubuntu). The base game, nwn, works fine. You just need:
1) nwclient129.tar.gz (from Bioware) (about 15 MiB)
2) English-somethingsomething-hotu-169.tar.gz (substitute your language as needed)) About 515 MiB
3) lots of patience

1) Install Game
2) extract nwclient129 into the nwn directory. I installed mine to /media/MT (a scratch drive)
tar zxvpf nwclient.tar.gz -C /media/MT/nwn
3) follow same procedure for the 1.69 HotU file. Note that this is the same as installing the critical rebuild patch.

The nwserver does not have a graphical interface. You'll need to type all your parameters in the command line. If you game locks up, you'll likely have to drop to a tty to run
killall -1 nwmain (-15 doesn't work, and -9 is too rude). If you do have to drop to a tty to adjust server runtime variables, when you return to the game you will have an X11 cursor in the center of your screen (i.e. a stuck virtual cursor). If you have a mod with the space in the name, no problem, just put quotes around it. Make sure case matches, for instance:
./nwserver [extra options here] "My Module of Coolness"

However, if your mod has a space in the HAK that needs to be loaded - and the hack has a space or case was not preserved, your module won't load, and I believe that you'll have to mod it and change the hak and/or remove spaces. Don't know for sure, haven't had time to test.

Hope some of that is useful.