Microsoft provides a new installer for the CDB Debugging Tools, which must now be installed as part of the Windows SDK. (http://msdn.microsoft.com/en-us/windows/hardware/gg463009/ that's where all the links now redirect to)
The installation path for these tools has changed too, they're now installed by default under C:\Program Files\Windows Kits\8.0\Debuggers\x64 and C:\Program Files (x86)\Windows Kits\8.0\Debuggers\x86
Neither of those is recognized by Qt Creator (2.4.1 and 2.5.0-beta), and the path to CDB can't be set for automatically found toolchains.
The only way I could get Qt Creator to find the CDB program was by manually copying the folder above to C:\Program Files\Debugging Tools for Windows
The new paths should probably be added internally, or we should be able to override that path even for preset toolchains.