It might be worth pointing out that one can change that default location of the My LiveCode folder. It may be obvious, but perhaps not to everyone?

>change that default location of the My LiveCode folder
10 years later: how do you do that?

Quit Livecode in case it is running.
Create a folder at a location of your choice on your hard disk.
Rename it to 'My Livecode'.
Either copy the content of the old 'My Livecode' folder to the newly created one or leave the new folder empty if you want to 'start from scratch'.
Restart Livecode.
Go to Livecode Preferences and under 'Files & Memory' -> 'User Extensions'. select the newly created folder as extensions folder.
Close the preference settings and you are done.

If you are using Livecode on several machines (not at the same time) and you could create the My Livecode folder in your Dropbox folder in case you are using Dropbox. This way you could use the same extensions folder without the need of installing plugins twice or so.

Thanks Matthias;
FWIW: one doesn't have to call the folder 'My Livecode'; it seems it could be any name.

Yes, i know. But i prefer to name it using the default name. Makes it easier to remember to find it, if you use the default name. ;) That's reason why i used it in my little 'instructions'.