Playing hd videos with lag problem

[FirstAidKit]

Hi guys, i am having a problem.
I hope u can help me solve it =)
Apparently i am having playing video with lag problem..
I am SNSD's lover so i hav downloaded all thier mv and live concert video into my pc. and some of the video is in hd form. I found that when my wmp12 or itunes play hd video , it occurs lag problem, like it will freeze for 1 or 2 sec and den normal back den freeze for another 1 or 2 sec
and i also encounter the sound comes first but the screen does not show the mouth is moving. U know wad i mean, right?
play normal video which is not hd form no problem for me, it plays smooth.
Can anyone help me, i wan hav a better performance for my video, cause i realli like them

ur kind help is appreciated =)

 

[FZ21Z]

Hi.

It will help if you could fill THESE in. Have you just installed Windows, 32 or 64 bit, have you run Windows update?

 

[FirstAidKit]

How to insert picture here? i wanna show u my dxdiag.
sorry, i am new to here

 

[Conan Troutman]

 

[FZ21Z]

http://www.sevenforums.com/general-...ed-method-uploading-posting-screen-shots.html

 

[FirstAidKit]

here's my spec =)