i have a netbook with a 720HD support, but how can i play downloaded movies at 720 without it being choppy?

i tried using vlc player for a 720hd movie, but it was all choppy, my
computer can support 720, so is there anyway i can play the movie at
the quailty without it being choppy and lagging? im using a acer
aspire one 522-bz623 model POVE6 netbook. and has a AMD Radeon HD 6250
(Fusio graphic card.