Joe wrote:

> We are planning on offering our application as a hosted
> solution, using Windows Terminal Services. We will need
> to put together a test server, and then hopefully once
> it's stable, be able to buy more identical servers, and
> replicate them with a hard drive image, so that we can
> easily add more customers as demand grows. [...]

This is the sort of thing that would best be solved using
virtualisation. You want high end hardware running
VMware http://www.vmware.com (see ESXi Hypervisor etc.)
or Citrix http://www.citrix.com (see XenServer)

You can easily replicate your configurations for new
servers and easily adjust each virtual server to offer it
the resources needed for a particular customer. Both of
the above offer management solutions for datacenters
running virtual server farms.

Go that way and most of the rest of your questions come
down to testing what works best for your particular
application (as usual, performance optimisation is
something that tends to be very application specific,
you choose what works best for the way your application
works).

--
Geoff Worboys
Telesis Computing