I've got similar problems on a T400 with hybrid graphics running Windows 7 x64 Professional, upgraded from Vista x64 Professional. I've upgraded everything to the latest (driver, bios, etc etc) using System Update.
When I boot up from cold, and switch to using batteries, the power consumption is around 8w. Very good.
Then I suspend, and resume from suspend, and the power consumption shoots up to like 20w. Horrible.
Then I manually switch to "High performance" and then back to "Energy saving", the power consumption comes back down, but to >9w, which is like 13% above the original 8w level. Acceptable, but not good.
This seems to indicate there're at least two problems with the power management aspect of T400 + Win7 x64:
First, there is the well-known problem that both internal and external graphics cards get turned on upon resume. Lenovo, please fix this problem. It's completely unacceptable to have to manually perform that switching every time one closes, and then opens the lid, or loss 60% of the battery life. And I do need to use the external GPU from time to time, so disabling it at BIOS level is not acceptable either.
Second, there is the more subtle problem that some other hardware/driver besides the graphics card makes the T400 draw an extra >1w upon resume.
I really wonder if these problems occur with T400 preinstalled with Win7 x64. If they do, shouldn't every major laptop review sites take notice of the defect and warn people. If they don't, then I do not really see why it's so hard for Lenovo to provide earlier users with the right driver/registry patch/etc to enable the correct behavior. As far as I know, these problems have not been fixed since Win7 came out.
Finally let me add that other that this, I'm extremely satisfied with my T400/Win7 system. The thermal dissipation, noise level, and durability are just top-notch. But this just makes the above mentioned problems more of a thorn in the side!
