Ganged = dual channel mode for ram. All cores get access to 100% of the ram.
Unganged = single channel. Each core gets access to a stick of ram. In theory, the unganged mode is better as each core will get access to data quicker. Also, it also allow you to control the clocks independently from each other.
I would run unganged for an AMD build, as it seems to run better from my experience.
The thing I would take out of the article is the concern of stability by making your "32-bit system" into a "64-bit system". I would recommend against it. If this is something you truly want, I would do a Google search on how to or hopefully a member will post you directions on how to do it.
How much RAM have your installed in your PC? If you are only seeing 4GB but have more than that installed, there might be issues steaming from PAE. If you only have 4GB and it sees 4GB, you are good to go!