We initially received good reviews on Windows Server 2003 Service Pack 2 -- now that goodness may be more apparent than real. It seems that if your NIC supports receive side scaling and you install SP2, your ISA Firewall turns into a worthless piece of steaming Windows Server 2003 SP2. ;)
The solution? Try this:
Oh, wait a minute. You don't know if your NIC drivers support RSS? Well, as the Windows Server 2003 SP2 team would say, "it sucks to be you!"
Why in the world would the SP2 team enable something this by default? Sounds like the same guy who was asleep at the wheel and they turned on the NAT-T bug by default.