I decided since
Virtual PC 2007 RC was out, I'd give Windows Vista another try. Everything had been working OK for the last couple of days. However, when I came into work this morning, plugged everything up to my laptop and booted up, Vista decided to change my monitor orientation and rotate both my laptop display and my second monitor 90 degrees. Not only that, but it changed my mouse so that when I moved it up and down, the pointer moved side to side (which of course is up and down relative to the new orientation). Trying to navigate the display properties under this condition is like trying to trim your ear hair using two mirrors (oh wait... maybe you didn't need that mental picture).
Here's the nice part. Under display properties (Control Panel -> Personalization -> Display Settings), monitor rotation/orientation was no where to be found. I started to Google the issue (by now turning my head and half my body totally sideways). I found some tips for certain display drivers that use keyboard shortcuts to change monitor rotation, but this didn't work for me.
After digging around, I finally found something. Under Control Panel -> Tablet PC Settings I was able to change the screen orientation to "Primary landscape." That fixed my laptop display, but didn't fix my 2nd monitor. To fix the secondary display, I found that when I went to Control Panel -> Windows Mobility Center, and then clicked the button for "Connect display" for External Display, it magically rotated back to landscape.
How's that for intuitive??