Installed video card, broke video playback

[Pooh21]

suffering pr0n withdrawal. deactivated my old ati onboard video card for a new nvidia 6600 everything works except, no more avis, divx or mov files play anymore. Should I reinstall the old ati drivers? Can my system run with 2 cards?

[Roscoroo]

did you renew direct x ?  (run,start,  dxdiag )

or you may have to reinstall all the codec's and perhaps divx and other veiwers

[mora]

Did you positively remove all old driver components? If not, then boot to safe mode and uninstall all ATI and nVidia display drivers with Driver Cleaner Pro:
http://downloads.guru3d.com/download.php?det=745

Then reboot and install nVidia drivers again, I've found these very good for 6600 GT:
http://downloads.guru3d.com/download.php?det=1279

If it still doesn't work, uninstall all codecs visible in "add and remove programs" and also uninstall video and audio codecs from device manager under "sound, video and game controllers. Then do a reboot, windows should re-install default codecs automatically. Then install FFDSHOW, which includes most common video and audio codecs, including DivX and Xvid:
http://www.afterdawn.com/software/video_software/codecs_and_filters/ffdshow.cfm

I hope your forearm doesn't wither because of this misfortune.