Well, I might as well give you a few suggestions on where to start:
Charles "Charlie" Chaplin:
Chaplin is accessible but he's rather too sentimental sometimes still a good place to start. Chaplin is also easier to get your hands on.
• The Gold Rush: (1925) Chaplin's "The Little Tramp" character goes panning for gold in the Klondike. The movie opens with a snake crawling up a mountain, except its not a painting, a special effect or a real snake - its a real line of extras climbing a mountain. The part where Chaplin boils and eats his own shoe is easily one of the funniest things I've seen. Chaplin added a narration, sound effects and a musical score for this release but there still is no dialogue.
• City Lights: City Lights' is a tad long winded but its one of Chaplin's most emotionally involving comedies. The Tramp falls in love with a young blind flower seller, only problem is she thinks he's a millionaire. When a cure for her eye condition is invented he promises to help her pay for the operation - if only he could find the money. This movie was made in 1935, long after the introduction of sound but still Chaplin made it silent.
• The Kid: The Tramp discovers a baby left in a dark alley by a pair of car thieves and begins to take care of him. This is one of Chaplin's funniest charming movies and is also autobiographical in some details. A soundtrack and occasional sound effect has been added by Chaplin in the 1930s.
Buster Keaton: The General is not the best place to start with Keaton, so here are the more accesible movies.
• Steamboat Bill, Jnr: William Canfield's parents were divorced so he grew up with his mother in Boston. His father is a big, strong man and his son a scrawney milquetoast. William tries to make his father proud by working on his riverboat but discovers with a shock that his girlfriend from college, whom he loves, is his father's biggest competitor. The climax of the movie is an amazing sequence in which William "Bill" is caught in a hurricane and the entire town comes apart around him.
• Our Hospitality: The movie begins with an idiotic piece of melodrama that sets this movie up. From there its one of the funniest movie I've seen. The Canfield's and McKay's are two families feuding, but young Willie McKay knows nothing about this. He grew up with his mom in New York. When he travels back to his birthplace to claim his father's estate he meets a young girl named Virginia who invites him to dinner. Unfortunately she is a Canfield and her father and brothers want to kill poor Willie, but due to the rules of Southern Hospitality they are not allowed to shoot him as long as he's a guest in their home. So all he has to do is stay in the house which is easier said than done. The movie includes a surreal train trip which you have to see to believe.
This is a good place to start, I think. Some of Keaton's shorts are usually included on these DVDs. Enjoy.