If you put a div around the menu you should be able to make the div full width and align the menu to the right without any problems. Right now your menu is directly in the content div, so that is why you are unable to position it the way you want.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.