Clay,
I think that the Paradigm Studio 40's are a superior choice to the Polk's. However, given the dimensions of your office, you may even want to consider the Studio 20's with a sub. Either way you go, you should be pleased with the Studio series.
(on a related note) I am also a big fan of having a nice audio set-up in the office. I shifted the Paradigm Phantoms I was using as my mains through college into my office when I replaced them with better speakers. In a year or two, I plan on upgrading my office set-up Studio 20's with a small sub.
Good luck with your purchase.
-Stephen