Yes you can. But some features are a bit... wrong. For example, the appraise skill doesn't work properly with the current patch in the OC, and all merchants will have an unfavourable reaction to you (I think).
But all the skills, feats, and classes will be available to you. Oh and don't go over level 20 in the original's campaign
can play the first nwn game with all the fetures of the expanson packs 
Linear Mode
