Well My Research shows that this is beyond sad- ALL ACPI System related devices seem to be using a Microsoft generic Driver that's been around since XP SP2, not only is it lazy both on HP and Microsoft it's almost criminal, for a multitouch tablet with all its capabilities to have drivers from 2006 is really disapointing if you other TM2 owners want to pursue this further, I installed sp46869 from HP' TM2 Driver (x64) Page and ran Intel's utility and updated the Chipset package to No avail.
"Microsoft Windows Management Interface for ACPI"
Driver Date: 6/21/2006
Driver Version 6.1.7601.17514
I tried the Update Driver process on all ACPI Indentified System Devices the only remotely related new Driver found was one for "Intel(R) ICH9M-E LPC Interface Controller - 2917" which Changed it from the 2006 Microsoft Driver to the 2009 Intel Driver.
I expect a great deal more capable Convertables and Slates humming along on Win7 will not beable to install the Preview let's hope Beta and RTM fare better
EDIT: Looks like we have a sucessful TM2 Owner http://www.youtube.com/watch?v=TzkYQ0Bkf3o