Hi EvilOzzmess.Welcome to SevenForums.
The following is from Microsoft:
The Microsoft® .NET Compact Framework 3.5 Redistributable contains the common language runtime and class libraries built for the .NET Compact Framework. In addition to version 3.5 support, it also supports applications developed for version 1.0 and 2.0. The .NET Compact Framework 3.5 provides new features such as Windows Communication Foundation, LINQ, SoundPlayer, new runtime tool support, and many other features.
and then :
In addition to version 3.5 support, it also supports applications developed for version 1.0 and 2.0.
That would seem, to me, to mean that 3.5 is backwardly compatible with the previous .NET releases. Download details: .NET Framework 3.5
With regards to the uninstalling of .NET :
There should be no problem in uninstalling .NET Framework
from your Windows system. Removing .NET Framework can be done simply through the Add/Remove Program or other uninstaller application
you might have.
However, it is possible that you cannot completely uninstall .NET Framework
due to some errors or issues you encounter during the installation. Corrupted or inclomplete installation of .NET Framework could cause it unable to be completely uninstalled.
Here is a link to an automatic cleanup utility to remove .NET versions that you wish to remove. Completely Uninstall/Remove .Net Framework with .Net Framework Cleanup
I would imagine that one of the many talented forumites will be able to give you better and more detailed advice but thought I would provide this info for you to have a look over.
Hope this helps.