I have problem, when converting Windows application from .NET2.0 to .NET3.5. 
I do this like so:
1. In Win XP I start VS2008 and open my solution project which consists of 4 projects;
2. On all of these 4 project Properties window in tab "Application" I select target framework value ".NET Framework 3.5"
3. I rebuild the solution, but all the old references to .NET 2.0 remains... It was written, that all the references after converting from 2.0 to 3.5 must be referenced automaticaly to 3.5 dll's, that are on my computer.

What I do wrong? Please help with some advice. Thanks