Visual Studio 2010 (and older versions) will remember the last target framework you chose when using File -> New -> New Project
. So if you create a new project using 4.0, the next time you create a new project 4.0 will be preselected as the target framework.
EDIT : Further to comment below:
Having looked at this a little more there is another solution that is slightly less faffy than the info on the link I posted in the comments below.
Create a new solution/project with the setup you need, then goto File -> Export Template
. After you have done there you can then use your new template when you go File -> New -> New Project
.
Seems to work, not thoroughly tested it though.
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