Check this out.

[How to: Prepare End User Computers to Run Office Solutions]
http://msdn2.microsoft.com/en-us/lib...US,VS.80).aspx

It explains the step to use VSTO 2005.

[Creating Office 2000 Solutions using .NET - The Code Project - .NET]
http://www.codeproject.com/dotnet/Of...singDotnet.asp

But according to the links above, you cannot use Office 2000 with VSTO. But some adjustment can be made to improve its use on Office 2000. Check it out for yourself.

Quote: "Traditionally, developers have used VBA to create Office based applications. When .NET came along with all its goodies, they felt the need for creating document-centric solutions with .NET. To address this need, Microsoft released Visual Studio Tools for Microsoft Office (VSTO), an add-on to Visual Studio .NET 2003 to create managed applications with Word 2003 or Excel 2003.
Visual Studio Tools for Office 2003 (VSTO) is a great tool to build Office solutions in .NET. Unfortunately, Office 2000 users cannot use this tool. This article is an attempt to fill that void. It shows you how to build Office 2000 solutions using Visual Studio .NET 2003. I have tried to keep the code as close as possible to VSTO 2003 so that you can easily migrate to Office 2003."

HTH.