If you find yourself unable to install VS2008 because of a failure to install the Web Authoring Component, this may help!
During installation of VS2008, setup would exit with a error - the log looked like this:
[08/25/09,17:02:01] setup.exe: [2] ISetupComponent::Pre/Post/Install() failed in ISetupManager::InternalInstallManager() with HRESULT -2147023293.
[08/25/09,17:02:02] VS70pgui: [2] DepCheck indicates Microsoft Visual Studio Web Authoring Component is not installed.
[08/25/09,17:02:02] VS70pgui: [2] DepCheck indicates Microsoft Visual Studio 2008 Professional Edition - ENU was not attempted to be installed.
[08/25/09,17:02:02] VS70pgui: [2] DepCheck indicates Microsoft .NET Compact Framework 2.0 SP2 was not attempted to be installed.
[08/25/09,17:02:03] VS70pgui: [2] DepCheck indicates Microsoft .NET Compact Framework 3.5 was not attempted to be installed.
[08/25/09,17:02:03] VS70pgui: [2] DepCheck indicates Microsoft Visual Studio Tools for the Microsoft Office system (version 3.0 Runtime) was not attempted to be installed.
[08/25/09,17:02:03] VS70pgui: [2] DepCheck indicates Microsoft Visual Studio 2005 Tools for the 2007 Microsoft Office System Runtime was not attempted to be installed.
[08/25/09,17:02:03] VS70pgui: [2] DepCheck indicates Microsoft SQL Server Compact 3.5 was not attempted to be installed.
[08/25/09,17:02:04] VS70pgui: [2] DepCheck indicates Microsoft SQL Server Compact 3.5 Design Tools was not attempted to be installed.
[08/25/09,17:02:04] VS70pgui: [2] DepCheck indicates Microsoft SQL Server Compact 3.5 For Devices was not attempted to be installed.
[08/25/09,17:02:04] VS70pgui: [2] DepCheck indicates Windows Mobile 5.0 SDK R2 for Pocket PC was not attempted to be installed.
[08/25/09,17:02:04] VS70pgui: [2] DepCheck indicates Windows Mobile 5.0 SDK R2 for Smartphone was not attempted to be installed.
[08/25/09,17:02:04] VS70pgui: [2] DepCheck indicates Microsoft Device Emulator version 3.0 was not attempted to be installed.
[08/25/09,17:02:04] VS70pgui: [2] DepCheck indicates Microsoft Windows SDK for Visual Studio 2008 Tools (x86) was not attempted to be installed.
[08/25/09,17:02:05] VS70pgui: [2] DepCheck indicates Microsoft Windows SDK for Visual Studio 2008 Headers and Libraries (x86) was not attempted to be installed.
[08/25/09,17:02:05] VS70pgui: [2] DepCheck indicates Microsoft Windows SDK for Visual Studio 2008 Win32 Tools (x86) was not attempted to be installed.
[08/25/09,17:02:05] VS70pgui: [2] DepCheck indicates Microsoft Windows SDK for Visual Studio 2008 .NET Framework Tools (x86) was not attempted to be installed.
[08/25/09,17:02:05] VS70pgui: [2] DepCheck indicates Microsoft Windows SDK for Visual Studio 2008 SDK Reference Assemblies and IntelliSense (x86) was not attempted to be installed.
[08/25/09,17:02:06] VS70pgui: [2] DepCheck indicates Microsoft SQL Publishing Wizard was not attempted to be installed.
There are a number of references to the issue on the web, but thanks to Neo from Microsoft Support, we finally tracked it down to a corrupt installation of Office 2007!
The solution was to uninstall all Office 2007 and Office 2003 components using the Windows Installer Cleanup utility, delete the files from "Program Files" and the Office files from "Common Files\Microsoft", and then VS2008 went on without a hitch. If you are experiencing the same fault, take a backup and think about trying the same thing.
All the best!