problem: VS2010 - "The install location for prerequisites has not been set" error - setup project error with .NET3.5SP1 as a prerequisite -

Problem:
An installer project that was originally created in VS2008, has the following error when built in VS2010:

The install location for prerequisites has not been set to 'component vendor's web site' and the file 'DotNetFX35SP1

Solution:
(
based on the Readme file for VS2008SP1 which is located here:
http://download.microsoft.com/download/A/2/8/A2807F78-C861-4B66-9B31-9205C3F22252/VS2008SP1Readme.htm#General Issues
)

1. download the .NET3.5SP1 redistributable:
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=22

2. open a command line prompt to the location where you downloaded the file dotnetfx35.exe
3. at the command line prompt, type the following:
dotnetfx35.exe /x:.

4. type the following:
explorer wcu\dotNetFramework

5. copy ALL the 5 folders + dotNetFx35setup.exe

dotNetFX20
dotNetFX30
dotNetFX35
dotNetFx35setup.exe
dotNetMSP
Tools


to the following location:

C:\Program Files\Microsoft SDKs\Windows\v7.0A\Bootstrapper\Packages\DotNetFX35SP1

6. The setup project should now build OK in VS2010.
note: you will probably get some warnings about the public key being different from that expected.

The post above descbribes altering the public key in product.xml file - however I did not do this as it does not seem strictly necessary.
The product.xml file is located here (for VS2010):

C:\Program Files\Microsoft SDKs\Windows\v7.0A\Bootstrapper\Packages\DotNetFX35SP1