work with Office 2000 under .NET 2003

Question

hello all!
i have the following problem. i have a C#.NET 2003 form, that lets me work with Word and Excel Docs. Writing this under Office 2003 and Office Xp I had no problems. When i need to do the same for the Office 2000 they have appeared.
So i created my program on a PC1, where .NET is installed, and Office XP PIAs too. i have selected the Microsoft Office Object Library 9.0 from the list of the COM objects, and have corrected my previous code (that worked for Office XP) for Office 2000 (number of parameters for Documents.Open (...) function e.g.). afterwards i created the setup project and launched it on the PC2, where Office 2000, .net Framework are installed. my program works fine, but when i press button1, that opens word document and does dmth with it, i get this message: Query Interface for interface Word._Application failed.
 with Office XP it was rather easy. I have found Office XP PIAs on Microsoft Site, and have done everything following the given instructions (i mean instruction as how to create the Setup project and let this work on the PC2 after just installing the program).
i would be very pleased and thankful to get answer from you because i need to solve this problem with office 2000.
Thanx in advance,
Andriy.