Many thanks to Sean Timmons for the Vlookup solution.

Using the same Excel 2000 worksheet, (I have two lists of data, both two
columns.
The first list is named "OurOrders" and contains an Order Number (Column B)
and Dollar Amount (Column C). The second list is named "TheirOrders" and
contains an Order Number (Column E) and a Dollar Amount (Column F)), how do
I
compare the two Order Number columns such that if Column E is not the same
as Column B, or is empty, Column B is formatted? Can I do this with
Conditional Formatting?

All help is greatly appreciated.
--
LPS