The game works fine (none of the pre-rendered cinematics work but whatevs)
and I wanted to see if multiplayer stuff is still around, but when I enter in the CD keys to the serial tool, the save and close/launch buttons are greyed out and I con only close the thing without it saving anything.

What am I missing here?
Thanks!

I don't know why, but the serial tool doesn't always work for some reason. You can still edit the necessary file manually, however. Search for the file nwncdkey.ini in the main folder of the game, open it with a text editor, and put in the codes (the order is the same as shown in the tool).

It's not apparent from your post which game you mean. The file-name above is for NWN 2. I don't remember if it is called the same in NWN 1, but it should be similar.

oh nwn2 lol sorry

Multiplayer is alive and well, but if you want to use it, you need the NWN2 Client Extension.
http://social.bioware.com/forum/1/topic/161/index/3116438

The built-in multiplayer used Gamespy, and they shut down their service earlier this year. The Client Extension replaces it.