Fredrik,

Do you mean one project with two solutions in VBA6 or .Net VS?
Jonathan

The following code will open excel and add a new workbook.  It works
for both Office 2000 and Office 2003 (only have access to those
versions currently).

There may be instances in the object model where versions are not
compatible, but for most of the basic functions they are compatible.
For example I also have New Email, New Task, and New Appointment
working for Outlook 2000 and 2003 as well as Mail Merge and Opening of
Word documents in 2000 and 2003.  This is using the same application
executable on different machines.  You should only need separate
assemblies if you are linking to the managed office assemblies, and
they are only available for Office XP and Office 2003.  I have to
target Office 97 onwards unfortunately.

Type _ExcelType = Type.GetTypeFromProgID("Excel.Application");
System.Object _ExcelObj = Activator.CreateInstance(_ExcelType);

object[] args = new object[1];
args[0] = true;
_ExcelObj.GetType().InvokeMember("Visible", BindingFlags.SetProperty,
null, _ExcelObj, args);

System.Object _BookObj = _ExcelObj.GetType().InvokeMember("Workbooks",
BindingFlags.GetProperty, null, _ExcelObj, null);
System.Object _Document = _BookObj.GetType().InvokeMember("Add",
BindingFlags.InvokeMethod, null, _BookObj, null);

cheers,
Jeremy