After renaming the section /Software/Microsoft/VisualStudio/8.0 to "8.0.old" I was able to run the GAXTroubleshooter, this is what it says:
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GAX Troubleshooter
Developed in 2007 by Clarius Consulting
Dumping OS details...
OS version: Microsoft Windows NT 5.1.2600 Service Pack 2
CLR version: 2.0.50727.1433
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Dumping GAX hive...
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Key: HKEY_LOCAL_MACHINE\Software\Microsoft\Guidance Automation Extensions
Value CurrentVersion=1.3 - (String)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\Guidance Automation Extensions\Compatibility
Value 1.1=1 - (DWord)
Value 1.2=1 - (DWord)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\Guidance Automation Extensions\Hosts
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\Guidance Automation Extensions\Hosts\VisualStudio
Value CurrentHive=9.0 - (String)
Value CurrentInstallDir=C:\Programme\Microsoft Visual Studio 9.0\ - (String)
Dumping GAX Main Manifest...
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<?xml version="1.0" encoding="utf-8"?>
<RecipeFramework SchemaVersion="1.0" TraceLevel="Error" xmlns="http://schemas.microsoft.com/pag/gax-manifest">
<Hosts>
<Host Name="VisualStudio" InstallerType="Microsoft.Practices.RecipeFramework.VisualStudio.RecipeFrameworkInstaller, Microsoft.Practices.RecipeFramework.VisualStudio" />
</Hosts>
<GuidancePackages>
<GuidancePackage Name="MetaGuidancePackage" Version="1.0" Caption="Guidance Package Development" Description="" Host="VisualStudio" Guid="23FC29C9-FAFE-47f1-B633-B548E788DDDF" ConfigurationFile="C:\Programme\Microsoft Guidance Automation Toolkit\Microsoft.Practices.RecipeFramework.MetaGuidancePackage.xml" Timestamp="633208681660000000" />
</GuidancePackages>
</RecipeFramework>
Dumping GAX info for 8.0 hive.
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Dumping PublicAssemblies 8.0 folder...
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The directory PublicAssemblies does not exists.
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Dumping GAX info for 9.0 hive.
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Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\Packages\{77d93a80-73fc-40f8-87db-acd3482964b2}
Value ID=1 - (DWord)
Value MinEdition=Standard - (String)
Value ProductVersion=1.0 - (String)
Value ProductName=recipe framework - (String)
Value CompanyName=Microsoft - (String)
Value InprocServer32=C:\WINDOWS\system32\mscoree.dll - (String)
Value Class=Microsoft.Practices.RecipeFramework.VisualStudio.RecipeManagerPackage - (String)
Value CodeBase=file:///C:/Programme/Microsoft Visual Studio 9.0/Common7/IDE/PublicAssemblies/Microsoft.Practices.RecipeFramework.VisualStudio.DLL - (String)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\Packages\{77d93a80-73fc-40f8-87db-acd3482964b2}\SatelliteDll
Value Path=C:\Programme\Microsoft Visual Studio 9.0\Common7\IDE\PublicAssemblies - (String)
Value DllName=Microsoft.Practices.RecipeFramework.VisualStudioUI.dll - (String)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\Packages\{77d93a80-73fc-40f8-87db-acd3482964b2}\Templates
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\Packages\{77d93a80-73fc-40f8-87db-acd3482964b2}\Templates\{23fc29c9-fafe-47f1-b633-b548e788dddf}
Value LastTemplate=4 - (DWord)
Value PackageName=MetaGuidancePackage - (String)
Value 1=C:\Programme\Microsoft Guidance Automation Toolkit\Templates\Items\Action\Action.vstemplate - (String)
Value 2=C:\Programme\Microsoft Guidance Automation Toolkit\Templates\Solutions\GuidancePackageSolution.vstemplate - (String)
Value 3=C:\Programme\Microsoft Guidance Automation Toolkit\Templates\Solutions\Projects\GuidancePackage\GuidancePackage.vstemplate - (String)
Value 4=C:\Programme\Microsoft Guidance Automation Toolkit\Templates\Solutions\Projects\GuidancePackageInstaller\GuidancePackageInstaller.vstemplate - (String)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\AutoLoadPackages\{ADFC4E64-0397-11D1-9F4E-00A0C911004F}
Value {53544C4D-E3F8-4AA0-8195-8A8D16019423}=0 - (DWord)
Value {77d93a80-73fc-40f8-87db-acd3482964b2}=0 - (DWord)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\AutoLoadPackages\{ADFC4E64-0397-11D1-9F4E-00A0C911004F}\Packages
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\AutoLoadPackages\{ADFC4E64-0397-11D1-9F4E-00A0C911004F}\Packages\{23fc29c9-fafe-47f1-b633-b548e788dddf}
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\AutoLoadPackages\{F1536EF8-92EC-443C-9ED7-FDADF150DA82}
Value {C9DD4A57-47FB-11D2-83E7-00C04F9902C1}=0 - (DWord)
Value {77d93a80-73fc-40f8-87db-acd3482964b2}=0 - (DWord)
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\AutoLoadPackages\{F1536EF8-92EC-443C-9ED7-FDADF150DA82}\Packages
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\AutoLoadPackages\{F1536EF8-92EC-443C-9ED7-FDADF150DA82}\Packages\{23fc29c9-fafe-47f1-b633-b548e788dddf}
Key: HKEY_LOCAL_MACHINE\Software\Microsoft\VisualStudio\9.0\ToolWindows\{90e51bf7-d80a-4fa1-8a20-2641cbb842f4}
Value Name=Microsoft.Practices.RecipeFramework.VisualStudio.ToolWindow.GuidanceNavigatorWindow - (String)
Dumping PublicAssemblies 9.0 folder...
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Microsoft.Practices.Common, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.ComponentModel, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework.Common, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework.Library, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework.PackageManagement, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework.VisualStudio.Common, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework.VisualStudio, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.RecipeFramework.VisualStudio.Library, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Microsoft.Practices.WizardFramework, Version=1.3.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
Unable to get assembly info: Microsoft.Practices.RecipeFramework.VisualStudioUI.dll - Im Modul wurde ein Assemblymanifest erwartet. (Ausnahme von HRESULT: 0x80131018)
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I am still not able to install a GP because the installer doesn't find a VS installation.