Need assistance with version independent Office Interoperability

Question

I posted a thread in the office interoperability section, but it appears to get almost no traffic, I have recieved no replies. I hope it will get more attention here, I could really use some help on this problem!

I have an application which I wrote which interacts with a few Excel spreadsheets. in a nutshell it takes a filled out spreadsheet in a certain defined format, and converts it to the latest template as we create new templates.

the program works as it is now, but its designed for office 2007. All of my users however may not be running 2007, I need to make this program compatible with 2007 and 2003 at least, it but the more versions of office it will work with the better. some machines which may need it are still running office 2000. I need to implement some kind of late binding technique to allow the application to use the Excel interoperability features of any version of Excel. I would appreciate it if someone could help me with what I need to do to modify my app.

thanks!