Hello Bob,

Because there is no preset target name for VS addin folder, we must have to
create a custom folder with DefaultLocation property
([PersonalFolder]\Visual studio 2005\Addins]) in setup project. Jim Glass
has a good post giving detailed instructions for building a setup project
for a Visual Studio 2005 Add-in.
You may refer to
http://blogs.msdn.com/jim_glass/archive/2005/08/18/453218.aspx
[Deploying Add-Ins]

Hope this helps. Please feel free to let us know if there is anything
unclear. We are glad to assist you.
Have a great day,
Best regards,
Wen Yuan

Microsoft Online Community Support
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See also this discussion:
http://tech.groups.yahoo.com/group/vsnetaddin/message/3327

There are some potential problems mentioned that you should take care
of. Especially with non-English OS versions.