[chompalomp2]

すごい changing to すごく is just like 早い (はやい, quick) changing to 早く（はやく, quickly）. By itself, すごい means amazing or brilliant, and by changing the い to a く, it is just like adding "ly" to the end of the word in English to make amazingly, or brilliantly, or more casually, "very", like Harold said.