DSotSC is one of teambgs mods.
www.teambg.com , hit the mods link to the right and pray that their forums are up at the moment.
AS for how good it is, I havent played the main part, but the little I saw of it before complete HDD meltdown was pretty good. Seems stable. You have to start the game with DSotSC installed, you cant sart a game and install later. Its not a huge download, although fileplanet queues are never fun.