Dimension 4700 Ram

does anyone know ......what is the max amount of RAM i can put in a Dell Dimension 4700.....i currently have 1gb.....256 in 4 slots..........also.....i've noticed that 400mhz is scarce .....Newegg and Tiger dont even list any.......i found it on Pricewatch......can i get away with 533mhz ?????? or should i go with Pricewatch ????.......i know i can get away with some over clocking.....but not sure how much