Like many other Thinkpad customers, I have noticed that battery life with Windows 7 is poor. The CPU fan on my X200 never shuts off. I think that's a pretty conclusive sign that something is wrong.
A few things I found that might help others:
The powercfg.exe utility is very useful. Start a Admin cmd shell (type cmd in start menu search box, right click and "Run as administrator"). Setup your laptop for maximum power savings. Run the command "powercfg.exe -energy". Open the output file in a browser.
I found that some driver had set the system timer to a short interval rather than the default 15 ms. I used the SysInternals clockres utilty to track down the problem. I used the "Device Manager" (under the control panel) to disable drivers until I found the culprit. It turned out to be "HDA CX20561 Soft Modem".
Disabling devices seems to be a good way to find some power hogs. With a bunch of drivers disabled I got the power consumption down to about 6.7 watts (from about 11 watts). It turns out that the "11b/g/n Wireless LAN" device is quite a hog). I'm going to see if I can adjust some setting to improve it.
The RightMark RMClock utility is fun to play with. It provides a lot of details and a lot of knobs to tune with. I found that using the "Performance on demand" profile worked well. I enabled the SuperLFM (6.0x, 0.9v) state, checked "Use P-state transitions 0,2,3,4", unchecked "Use throttling" (I think throttling is useless on a Core Duo). The graphs on the monitoring page are useful. Before disabling the soft modem, the CPU was ending up in a low frequency state but the CPU and OS load were jumping up quite a lot.
I seem to get the lowest power use with Power Manager rather than RMClock. With the WiFi switch turned off and screen turned down, the "Battery" page of Power Manager says 6.3 watts right now.
