Be advised that Dark Side is a bit buggy. I have found it frequently crashes when an enemy approaches upon first entering a new map--about half the time only to the desktop, thank goodness. But the whole slew of BG2 caliber spells and weapons make it well worth it, as far as I'm concerned. You have to start a new game to play it. You can download it from
http://www.dsotsc.com/index1.shtml (I'm having a grand time playing party of paladins with DS, but I'll shut up about that already, lol.)