Video Problem

I have P-4 1.6GHz,Intel D850 board,external SIS300/305graphics card,128MB RD RAM. Any movie file in Windows Media Player(WMP)is not working fine. it is playing it in frames and the sound also jumps in frames with picture. although the same file is working fine in Xing Player. i have already tried with reinstalling windows and also changing to WMP9.0 but still no effect. kindly suggest a solution.