Qt Creator can't find any valid Qt versions

Question

I'm trying to use Qt Creator, but it is not working. My hello world application gets the following error:

No valid qt versions found.
Please add a qt version in Tools/Options or via the maintenance tool of the SDK.

In Tools → Options → Tool Chains, I see the auto-detected compilers:

MinGW runtime (provided with Qt creator)
Microsoft Visual C++ Compiler 9.0(x86)
Microsoft Visual C++ Compiler 9.0(amd64)

Googling, I see that it's a bug of Qt Creator but I can't find a fix.

How do I get Qt Creator to work?

Solution

For Qt Creator 2.4.0

If you find a valid Qt installation under Tools > Options > Build & Run > Qt Versions. If you have no valid Qt installations here you might need to rebuild from source or download the procompiled libraries from qt.nokia.com and add them manually.

When you have a valid Qt installation showing up there which one to build against by opening the Projects tab on the left sidebar. Under Build Settings > General you can select the Qt version AND which toolchain to use for various builds.