go to one of the italian groceries (dave's on 30th ave around 34th or D&F on broadway around 37th) -- you'll find a variety of what you're looking for.
do you mean a restaurant to eat at or a pasta place to buy it at? if you want to buy, it the best is Cassinelli on 23rd Avenue in between 31st Street & 33rd Street. They also make the best fettucini.