Natty starting to look a lot better -- even usable.

Yes, amazing what difference a day, and a lot of googling and reading, can make.
Now I have very functional incarnations of Natty Beta1 on both the Dell E520 desktop and on the EeePC 901 netbook.
The main points I learned to get this far were:
1. Unity is activated by the Ubuntu Unity Plugin in ccsm
2. The reason I lost Unity from the EeePC was that I had activated Desktop Cube and Rotate Desktop in ccsm. These are incompatible with the Unity plugin so it got disabled unbeknownst to me.
3. However, Wobbly Windows cause no problems to Unity in the 3D version fo Unity which I'm using on the EeePC. Additionally, water effects work but the effect itself just doesn't seem quite as smooth and watery as I'd seen it before. Still acceptable, though.
4. On the EeePC901, the graphics driver is i915 for the video card Intel Corporation Mobile 945 GME Express Integrated Graphics Controller.
5. The Dell E520 has a nVidia GeForce 7300 LE graphics card and uses the nvidia driver module which I believe corresponds to the nVidia 270.29 driver. However, 3D effects are not available with Unity. If I select the Ubuntu option at the login page, a totally non-functional page results.
6. To get things working on the E520, I selected the Ubuntu Safe Mode which, strangely, was nothing like the safe modes I've seen before (single-user mode). Basically, it was a conventional GUI desktop but without 3D effects.
7. To get Unity however, it was necessary to install unity-2D from Synaptic and reboot. Now, on the login page, a Unity 2D option is provided. This works very well as can be seen from the screenshot (grey wallpaper).

Although Unity was originally aimed at the smaller netbook screen sizes, I believe it fits better on my 1920x1080 desktop monitor.