iTunes Video and Audio out of sync for Movies and TV Shows

[ew6050]

I love my x301 but I travel a lot and watch a lot of shows and movies on long flights via iTunes. I have Windows XP.
My only pet peeve is that the lips and the audio are always slightly out of sync. Is that likely a function of the the low energy processor, lack of a discrete video card, hard drive speed, or something else entirely? I know iTunes is not viewed as the best application in terms of overhead and efficiency but on my other Windows machine (HP EliteBook 2730p tablet - spec link at end) I never seem to have this problem.

Any thoughts?

Thanks.

HP Specs: http://h10010.www1.hp.com/wwpc/us/en/sm ... 84558.html