I found this in a few different places around the 'net - hopefully it's helpful:

Stop Jerky Graphics

If you are connected to a LAN and have problems with jerky graphics, this might be the solution:

  • Right-click "My Computer".
  • Select "Manage".
  • Click on "Device Manager".
  • Double-click on your NIC under "Network Adapters".
  • In the new window, select the "Advanced" tab.
  • Select "Connection Type" and manually set the value of your NIC. (Not "Auto Sense" which is default.).
  • You should reboot.

Another reason might be the zip drive. In my case it was an old parallel zip drive. I am running Windows 2k Patch 4 and a geforce graphics card. After disabling (resp. removing the zip; who needs it anyway anymore?) the graphics were as smooth as they used to be.

I don't have "Connection Type" as one of my options, I have:
Link Speed/Duplex Mode
Network Address
Receive Buffer Size

I'm thinking Link Speed/Duplex Mode could possibly be the same thing, the options for this are:
10 Full Mode
10 Half Mode
100 Full Mode
100 Half Mode
Auto Mode

Which of these would be the correct setting (assuming I'm correct in my assumptions, lol)?