When i try to play HD video in my 64bit pc's WMP 12. It's not that smooth.. But when i play the same file in VLC player it works fine. I tried replacin Klite codec pack with win7 codec pack...but still the same. amazingly the same video is cool in 32 bit XP.. My PC's Specs: intel core i7 2600 @3.40 ghz RAM 8.00 gb 64 bit OS NVIDIA geforce GTX 550 Ti (the above mentioned HD video is my own product exported from Adobe Premier Pro cs4) Any help Appreciated. Thank you.