I just installed Windows 7 on my (Thinkpad) Lenovo T400, it works like a charm. I struggled a bit with the switchable graphics though, because I dock my laptop and use the xdvi cable. All I got was black screen when I downloaded the drivers from Lenovo.
What I did then was disable the switchable graphics in the BIOS, booted and updated the drivers, I did this via the Lenovo updater. I updated everything and installed the Lenovo software, except the Vista patches. When I tried to install the Vista patches the machine went into blue screen.
After updating all drivers I enabled the switchable graphics again but it didn’t help, no matter what I tried.
But then I right clicked the power symbol, chose “Switchable graphics” and high performance, answered yes and there it was. Now everything works fine.
There is still a problem when I close my laptop while Windows 7 is running, if I do that and open it the screen is black. I found out that I had to press the power button and put it to sleep again, and then wake it up by pressing the power button again, then the screen is ok.
Remember that the System updater still think you run Vista, ignore that and install the updates that arrives for it on your new Windows 7 – but don’t install the ones that say “Windows Vista Update Module”. 
Update: You can now download version 4 of Lenovo’s update software, it will now recognize your Windows 7 system and be able to update drivers. It worked like a charm.
Update : September 9th a new version of the ATI drivers were released. Check out version 03.00.0741 special designed for Windows 7. It makes Switchable graphics a little easier to use. I had to fiddle a bit with the settings though but your setup will feel more “windows 7 native”.
Update: Now I got the accelerometer to work too, I had to download the latest drivers via Lenovo update software.
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I am having some difficulties with the switchable graphics. When I dock my pc and boot I have to manually enable high performance to get my xdvi display to work. I hope there will be a fix to this.
hi, i’m currently working on the setup of my T400 with win7, but i cannot follow your installation procedure.
which updater from lenovo did you use? the one for vista? if i start that one, than the update brings up everything for vista 64bit (i have win7 ult 64 bit installed).
currently i cannot get the ati-card running. but i need this as i’m most of the time on workplaces with docking station, so the switchable feature is not the highest priority at the moment.
I used the one for Vista. The Lenovo software thinks you are running Vista, ignore that. But only install the drivers, not the ones named “Windows Vista update module”.
I guess it will take a while before the software recognize that we run Windows 7 and not Vista, it just checks some version number now.
I just completed the upgrade on a t400 to windows 7. I did a clean install and then used the ThinkVantage System Update 4.0 this will update and download all the needed drivers and is very easy.
Thanks Phil for the heads up, I didn’t know it was released yet. It worked like a charm.
I had windows 7 on my thinkpad x61s and it worked great after downloading all the software updates. Did T400 come out before the x61s or after?