HD Videos playing slow and low quality

i just installed vista and the videos i have on a external drive are now playing quite slow and lower quality then they were a few days ago on xp, iv downloaded media player classic, vlc and divx. i also installed ffddshow and klite codec pack....any ideas what else i can try?

 

hp compaq dc5100 SFF (pw187et)

on the dxdiag under display direct draw etc is not there it says not available so not sure if that is it? streaming vides play ok, just downloaded videos are slow and low res even there hd so maybe a new video driver i can download?

 

Hi my friend , go to Start - Run devmgmt.msc - Ok
Is there any ? in Device Manager menu ? :wave

 

hey bud
nope no yellow question marks, there was yesterday for ethernet and audio but i downloaded random files and managed to fix that...so im guessing i maybe installed a crappy chipset or driver? the whole pc seems to be slow now especially mozilla which was normally really fast

 

awesome thank you, do i download every single driver or just the video/graphics?

 

slight problem, the video refresh one installed no problems, but the main one says the NVIDIA setup program could not locate any drivers that are compatible with your current hardware, setup will now exit