There are multiple versions of vcredist available. Since the dll's are installed in a side by side manner it is important to get the version that you've built your manifest with.
2.0.50727.42 Initial VS release
6.0.2900.2180 XP SP2 release (drops ver 2.0.50727.42 files)
2.0.50727.762 VS SP1 release
From what I can tell only the 6.0.2900.2180 file is available from MSDN currently. The other versions can be retrieved from a visual studio installation at "%PROGDIR%\Microsoft Visual Studio 8\SDK\v2.0\BootStrapper\Packages". Different versions of visual studio may utilize different directories, I have sp1 installed.