Running "ipconfig /flushdns" should clear that list, meaning it should be fairly short when you do the "ipconfig /displaydns". If that's still too long, then we'll have to change the buffer length.
When you open the command prompt, right click on the title bar at the top and go to properties. Go to the Layout tab. In there you should see a screen buffer size that, by default, is set to 80 wide and 300 long. Width isn't really a problem, so lets change the length to something a bit more usable, like... 9999 or so.
(Just because most every machine I use at work ends up with that setting at some point...300 lines is never enough...though you would probably be safe around the 2000 - 3000 range)
Once you've done that, try running the previous commands again:
Also, I would suggest closing anything else that you might be running that might use the network. That should help clean the DNS list as well.