Upgrading to Win 10 Pro RTM (not the beta) on a T400 was definitely more painful than any other recent Windows upgrade that I've experienced on desktops or other Thinkpads. The result is quite mixed, and you need to weigh the benefits and detriments, and be aware of the 'gotchas'. Dell Vostro Bluetooth Driver Windows 10.
My T400 includes the switchable graphics and a fingerprint reader. Reinstall Iphone Driver Windows 10 more. Canon Pixma Mp210 Driver Windows 10. Incompatibility of both of these with Windows 10 is the main reason that I'm reverting to Windows 7. I attempted 7 installations, including in-place upgrade of Windows 7 and fresh installs on a new partition.