So I installed Painter 11 (using the trial version, which worked for me), and found that running it on my Lenovo X60T doesn't give me any pressure sensitive support. So eventually I had to install the Tablet PC enable driver, which is PenTablet_505-7.exe. Now Painter 11 recognize the pressure sensitivity.
However, that does have some side effect. For instance, SketchBook Pro 2010 was affected as the pressure sensitive level changed. I would love to keep the original setting, but supporting pressure sensitivity on Photoshop CS4 and Painter 11 is also pretty important. I feel like I am simply picking the best of both evil.