DDP - can you give us a bit more detail about that formula?
I presume your data is in ranges L18:L104, M18:M104, and N18:N104, but what is in cells W7 and Z3?
General comment - I'm all in favour of keeping things simple, but writing a UDF really isn't that hard, and when you have done it the logic is much more obvious than it is for the clever but mysterious worksheet formulas that people come up with.
On XL 2007 - just for a bit of balance, some things that are better in 2007:
Tool tips and help when entering functions are much better.
Saves large files much quicker, and to much smaller size.
More stable with very big files.
It has more rows and columns.
Whether those features make it worth the hassle of the new interface is a matter of taste, but it simply isn't true that nothing is better.
Doug Jenkins
Interactive Design Services