Two of the best charts I have ever seen, that I just recently came across when trying to answer this question for myself. You migh want to save the images to your computer to be able to see the whole thing at once. My belief is that we are about to see stocks and the dollar fall together as they have more often than not during the last 20 years. Then, holding dollars will truly be a double-whammy.

It is from this well-written blog: http://marketthoughtsandanalysis.blogspot.com/2009/09/thoughts-on-us-dollar-analysis-of-usdx.html

Hysteria