Ok this is hard to explain but will give it my best

ok I have 2 excel sheets which contain client details - one is the list of clients who have been processed the other is those who "may" need to be processed - each client has a unique ID number

So what I need is a way of comparring the ID's from each sheet so if we have customer details ::::

Client Name RefrenceID Address
Mr J Smith  1101345678 123 someplace
who is on the list of customers who may need to be processed - I can take the refrence number 1101345678 and compare that to the list of completed clients - if the refrence is on the list of completed then I can strike him of the list to be done.

there is some 1000 that need to be done so manually going through and checking is something i would prefer not to do.

I can export from excel to access/txt/etc

but does anyone know of a quick and easy way of me doing this??