I generally believe that to fully understand a new system, it requires three installations; the first to familiarise yourself with the options and to see what's possible, the second to repeat the process with an understanding of what you want to achieve (ideally documenting as you go) and the third to implement properly (using the documentation if written during the second phase).
I try to apply this approach to all my projects at work, but didn't anticipate doing it for my home install. Learning SUSE required three installs, primarily because I broke the first two...
The first attempt was getting familiar with the operating system. In my enthusiasm, I installed, added loads of repositories and then updated loads of files. Somewhere along the line, something broke. I think it was a kernel upgrade. Either way, booting because erratic, sometimes getting to X (with a non-responsive mouse) and other times just hanging on the boot.
So I re-installed and didn't try to add the repositories initially. I carefully patched the system, checked it booted okay and then fiddled with Xgl. I knew that this was still experiemental, but was keen to see the effects. Massive problems with not having the right kernel source.
Third install - patch, add the full repositories, get the commercial Nvidia drivers, check all works okay (reboot just to be sure), then setup Xgl. All works fine.
Take backup of system!
Now everything seems to be working very well. Xgl is gorgeous and actually "feels" better than normal X. I'm still putting all my key applications back on (VMware Server, Skype etc.), but it's all very impressive.