If you already have 2 cards then SLI them, however, if I was making the choice right now assuming you had no cards, I would get a 1 card solution. SLI is merely a stop-gap solution for not having enough horsepower in one GPU (industry has been here before, remember the Voodoo2?). Anyway, I think that 1 card is better than 2 especially if you don't game 24/7.