If you wish to keep Power Commands for Visual Studio 2008 installed, see this workaround here:
PowerCommands crashing VS2008 SP1
But basically:
a work around which is a simple modification to the devenv.exe.config file.
This will exist in (64 bit systems) C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE
Or (32 bit systems) C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE
Add this XML token to the dependentAssembly list. They had me add it after the office one, but im not sure if that matters.
<dependentAssembly>
<assemblyIdentity name="office" publicKeyToken="71e9bce111e9429c" culture="neutral"/>
<codeBase version="12.0.0.0" href="PrivateAssemblies\Office12\Office.dll"/>
</dependentAssembly>
<!-NEW STUFF-->
<dependentAssembly>
<assemblyIdentity name="Microsoft.PowerCommands" publicKeyToken="null" culture="neutral"/>
<!-- For 64-bit systems, uncomment this one
<codeBase version="1.1.0.0" href="C:\Program Files (x86)\PowerCommands\Microsoft.PowerCommands.dll"/> -->
<!-- For 32-bit systems, uncomment this one
<codeBase version="1.1.0.0" href="href="C:\Program Files\PowerCommands\Microsoft.PowerCommands.dll"/> -->
</dependentAssembly>
This worked nicely for me.