my computer defrags its self. graphics are media accelaretor driver and it wont allow changes....graphics adaptor is 82945g express chipset family..... resolution 32 bit 1680x 1050

That's unusually high, more suited to a big screen high def TV.
For most videos, try 1024x768 in 24 bit colour, which
should be a good fit for your 64 MB video card.

To change the display resolution,

• right-click an open area on the desktop,
• hit "Properties",
• go to the Settings tab and hit the Advanced button.
• In the General tab there's three choices on the bottom half.
  Select the one that says "Apply the new display settings
  without restarting" and hit the OK button. That will drop
  you back to the Settings tab.
• Try new resolutions with the color quality set to 24 bit and
  hit the "Apply" button to try each resolution.

Don't worry if your monitor goes blank, because if you just
wait Windows will go back to the previous setting and you
can try again.

Play around with it for a while. You might as well get familiar with it.

If you want to buy something better there are plenty of
good choices. Virtually all of them are better than 64 MB,
with 256MB pretty much being the smallest right now.

Look for one with output jacks compatible with your TV, if
you have a good one. Home theatre is pretty cool.

While your mind is on video playback you might as well
upgrade your software. There are better players and codecs
out there and you can get a bundle with all the bells and
whistles for free. Here's one that I found useful:
Download K-Lite Mega Codec Pack

[The VideoLAN VLC media player] is also highly recommended.