It's a known issue that ClearType doesn't render text well when lcd monitors are rotated to portrait orientation. ClearType is primarily tuned for a vertically oriented RGB stripes (your average everyday LCD monitor in horizontal mode).
It would be awesome if I could find a monitor built for portrait orientation. i.e. a monitor that has vertically oriented RGB stripes when in vertical orientation.
Does anyone have experience using a monitor like this?
I plan on it being a fourth monitor that is used primarily for reading. It will sit in portrait orientation permanently.
FYI, here's a great article on ClearType in Windows 7. I've highlighted some of the discussion in the comments sections on vertical mode rendering.