So far, it's only the original unaltered trilogy.

After years of intense training, I've been able to basically erase the prequels from my head. When I watch the original Star Wars trilogy, I don't think of the prequels. Even when Obi-Wan does his speech ("And he was a good friend."), it just doesn't come into my head anymore.

I haven't watched any of the prequels since Episode III came out. Unless you count the Plinkett reviews. In which case... I've seen them countless times for the past couple of months =P

I'd like to give some of the novels/comics a try someday.