We do not use ISA. Our current configuration uses a Juniper DX Application Accelerator and the "SSLOffloaded" registry setting on our 2003 Front-end server to access our 2003 Back-end servers (as described in KB327800).
I am trying to setup something similar now that we have installed Exchange 2007 (only two of us on the 2007 server at this time until I get OWA working).
Installed are a 2007 CAS-only server and a second server with the CAS, Mailbox, HUB, and UM roles on it. I've been trying to configure the CAS roles to allow for "SSLOffloaded" and get OWA to work to the 2007 mailboxes. The CAS-only server does allow access to the 2003 mailboxes. Having made and reset settings so many times now I am now very confused.
I would greatly appreciate it if you could provide instructions on how configure our two Exchange 2007 servers to use the SSLOffloaded feature (assuming it still works)?