I'm writing a fairly large (~25k lines so far) VB program which works with Excel, and I haven't been able to figure out the best way of dealing with the fact that differed versions of Excel have different interfaces. I can either use interop for the oldest version of Excel or I can late bind. Both seem to work, but I don't know if there's a significant difference in efficiency, compatibillity with future versions of Excel, or some other way.

' any thoughts?

Thanks.