Visual Studio 2010 (and earlier versions) will remember the last target structure that you selected when using File -> New -> New Project. Therefore, if you create a new project using 4.0, the next time you create a new project 4.0, it will be pre-selected as the target structure.
EDIT: In addition to the comment below:
, , , , .
/ , File -> Export Template. , , , File -> New -> New Project.
, , .