Charles,
I have a very similar E8400 setup at home except I have an 8600GT video card and 4G of RAM. My Server 2008 Enterprise 32 installation runs beautifully with all the Aero effects enabled and I do not see high CPU usage on dwm.exe. Since dwm.exe is responsible for the 3D and transparency effects, I wonder if your video card drivers are causing problems? You might want to try either newer or older versions to see if it improves the situation.
I presume you have activated the Desktop Experience feature?
Doug
