migrating vs2008 app to vs2010

Question

hi,
i hav previously installed vs2008 with .net 2.0sp2 and .net 3.5 framework.
i upgraded to vs2010 but when i open the 2008 apps built with target framework 2.0 it wont open it and said that u have to continue loding this app to 4.0 , later u can change it by setting target framework to ur choice and their is no such option in project settings for changing the target frame work, as it is showing only 4.0 ,and i have 2.0 and 3.5 on this smachine as well,
same happen when  creating a new project in vs2010, frame work combo box in project setting is not pooping up other frame works except 4 as i have them on machine
plz help
regards