This was posted by a clever user on the Amazon forums. Essentially, it allows you to add points to the calibration process- as many as you like, to any part of the screen- to address specific parallaxes (pen to input point offset) issues. Here's the post: Ive solved it!! My slate also had some bad drift on the left hand side (when in landscape mode), when my cursor went near the edge it would be about 4mm off. What i did, and now it is perfect, was tweak the calibration tool. You can change the number and position of calibration points it uses, so instead of the usual 4 points it makes you touch, i made it use about 150 points, with lots of points along the side of the screen. You need to: 1. if you have installed asus's driver for it (the one from their website), you need to got to the control panel, programs and features, then uninstall it (i forget what it was called, but it starts with 'ISD'), and restart your tablet (after you uninstall it, the pen wont work, so either have a mouse plugged in or use your fingers). 2. go to control panel, open tablet PC settings. Reset all the calibration data (touch and pen). When all the data has been reset, the reset button will be misted. 3. open command prompt (click start and type cmd in the search box). 4. type in, (or copy and paste, however to paste in command prompt you need to click the little black box icon in the top left corner, then select edit, then paste). Type in (make sure its all on 1 line): tabcal lincal novalidate XGridPts=5,15,30,50,70,90,120,259,513,767,1021,1180,1210,1240,1275 YGridPts=5,15,50,100,163,223,321,479,640,740,780,795 Then hit enter, it brings up the calibration screen but with heaps of points for you to touch. Make sure your pen is the first thing that touches the screen, then it will calibrate for the pen. After you hit the first crosshair with the pen, then you can rest your palm on the screen and do the rest. Just don't rest your palm on the screen until you touch the first crosshair, otherwise it will calibrate it for touch. Fixed my issues 100%, now the pen is perfect in every part of the screen. So there. (Amazon.com: Customer Discussions: Asus EP121 poor pen and touch accuracy) Here's the next question, though: ISD_DualTouch_702-21 is the Wacom driver I found on these forms, recommended for users getting the BSOD. I don't have BSOD issues, but I'd like to be able to use the most recent driver from WACOM anyway. The trouble is, that driver comes with a WACOM calibration process to replace the one native to Windows 7 (which the trick above improves), and I don't know how - or even whether - the WACOM process can be similarly improved. The process described above will still run with the WACOM driver installed, but it runs the Windows calibration process, which I'm not sure has any effect with the WACOM calibration software present. This should (l hope) be useful to those of you who haven't upgraded your pen drivers. I'm curious, though, as to whether anyone here can do for the WACOM calibration process what was done for that of Windows. Very best regards.