I had this same problem. I fixed it by adjusting Windows so it lowered the level of acceleration on the video card (I have a cheap video card like most
cards that come with the machine).
Do this by right-clicking your desktop and choosing "properties".Go to the "configuration" tab.Select the "Advanced" button. Choose the "Troubleshooting" tab (it might be called "Performance"). There will be a slider that will let you raise or lower video acceleration. Drop it to nothing, accept the change, then launch the Rules Roundup. If you see the cows, this was the problem.Adjust the level up until it's at the highest acceleration where you can still see cows. I haven't noticed much change in performance in non-java programs.
If that doesn't work, you can go to the other JVM within IE from the Tools menu. Click "Options", then the "Advanced" tab. Partway down the list there will be a box to uncheck to stop using the 1.4 JVM plugin.
But in my case the 1.4 JVM plugin works fine as long as acceleration isn't very high.
Hope that helps.