The places for dlls have been nicely summarized by this post ( see also above ).
[quote author="Lukas Geyer" date="1309625643"]All dependencies (DLLs), including the Qt libraries, have to be placed in one of these "locations":http://goo.gl/FNXv9
bq. * The directory where the executable module for the current process is located.
- The current directory.
- The Windows system directory. The GetSystemDirectory function retrieves the path of this directory.
- The Windows directory. The GetWindowsDirectory function retrieves the path of this directory.
- The directories listed in the PATH environment variable.[/quote]
Certainly you can copy every time the exe and the dll to the desired directories. But with vs2010 you may want to create a "Setup and Deployment" project. If you add a project in vs you should have such a possibility under other projects.
As Zlatomir pointed out, you are using a debug dll with a release compilation? That should not happen.
One last important thing for distribution of your project's results are the license conditions.