Video won't play in media center but plays in wmp

I have a large section of videos and none of them will play inside of media center for windows 7. I have tried reinstalling, new codecs, removing codecs (ffd, k-lite mega, shark007) and no change to how media center works (the wmp wonlt play some with no codecs). I have used a tool to tweak the default codecs used in media center and no change. My video card is directx 9 compatable and windows advisor said it would work for windows 7 even though its only a 64mb card. Music plays fine and so does internet video. do not have tv hooked at all.

video card:
64MB DDR NVIDIA GeForce4 MX 420 with TV Out (Dell) [Display adapter]

1gig ram
Board: Dell Computer Corp.
Bus Clock: 533 megahertz
BIOS: Dell Computer Corporation A01 10/22/2002

Video card upgrade highly recommended.

I don't mind buying a new video card, but if this one is listed as compatable and when i run the windows 7 advisor it says it will work. So i am not sure its just the video card.

So i tried another video card and thats not it. I can play the videos fine in windows media player and in any other player i use in windows 7. When i start media center, it will not play. I have tried changing the default codec for media center, but still no luck. any ideas before i go back to xp?

i am having the same kind of problem, have you tried opening video files using SHIFT+Right click > open with > windows media center ? that works for me though.
check my post at
Videos will not play after watching tv