Hello Qubes folks:
I got Qubes R3 up and running on my trusty old Thinkpad X200 today. I've attached my HCL report.
This is a Core 2 Duo machine and supposedly supports VT-d, but I wasn't able to get Qubes to install until I disabled VT-d in the BIOS setup. X wouldn't start for the installer, and then the text mode installer would hang in weird places. Turned VT-d off, and everything installed without a hitch. I haven't tried going back in and turning it back on to see if Qubes will boot with it enabled.
This machine has a TPM, and the qubes-hcl-report tool sees it.
Qubes is very cool. I've always been a linux nerd, but the Snowden stuff has started to turn me into a privacy/security nerd, too. I'm kinda tied to my MacBook Pro for some of my work, but hopefully I can get my workflows up and running in Qubes and replace my Chromebook that I do most of my writing on (in Emacs via crouton) with some sort of Qubes machine soon.
Let me know if there are other reports I can make or things I can run to give you more X200 info. I love this machine and would love to see it fully supported!