Sorry guys - and thanks for showing me how to move my misplaced post here.
Found a portable semi-transparent on-screen ruler here: http://www.download.com/On-screen-Ruler/3000-2192_4-10520256.html?tag=lst-1
Being semi-transparent, i can easliy see what i am measuring (pixels, inches, cm). And being able to nudge it is useful.
Here's the blurb from downloads.com:
This program is a semi-transparent on-screen ruler with keyboard shortcuts to help you lay out GUIs and Web pages or measure anything on your screen. Right-click to learn the options and shortcuts. The ruler saves its settings upon exit, so it always looks the way you configured it last. The program comes with a built in uninstaller. It is safe for work, since it does not modify your registry.