Advantage of using Intel's Trusted Execution Technology

[fluffie]

can somebody explain to me in layman's terms:
if i use Xen with Intel's TXT, what advantage will it bring?
is it: 1) the hardware brings extra protection to the isolation between the different guest OS or
2) the hardware ensures in some way the guest OS is isolated from the host OS.
3) or simply TXT makes Xen run faster..?