Data Manipulation Problem

[Jez]

We have a 3-tier architecture. The lowest data tier is finalized and returns
to the middle tier (business logic), for example, a collection of employee
objects.

What is the best way to translate this collection of employees to a datagrid
on a form? I can return the collection to the UI layer via a property and
bind the grid directly to the collection, but what actually happens here at
run time? Are all employees in the collection transferred over the network
between layers or are records "buffered" in some way? How can I configure
which columns are displayed on the grid and their formatting?

Should I copy the collection into a datatable (in a dataset or on its own) -
at the business layer or the UI layer? Seems like overkill to copy the
collection over the network then make a copy of it at the UI layer. I need
to be able to ensure that data is buffered when the employee collection may
contain many thousands of employees and the user may only scroll down the
first 20 or so ... My inclination is that this should happen at the business
layer.

I'm sure this scenario must be a common one and there must be some useful
guidelines out there somewhere .... any pointers greatly appreciated.