The “simplest” way to do it depends a lot on your familiarity with WordPress, the *nix shell, MySQL importing/exporting, and the editing of PHP and possibly .htaccess files.
About every possible scenario for “moving Wordress” has been discussed, at length, in these forums. IF you use the forums “search feature” and select “all forums”, enter “move wordpress” (w/out the quotes), set the “search options” to “And”, and the “Date Range” to “All Posts”, you will find many of these potential move scenarios discussed, some at length, and resolved.
Alternately, the definitive guide to all things relevant to moving a WordPress installation from one place to another can be found in the WordPress Codex article on Moving WordPress, and they explain it better than I could. They go into a lot of detail, and give some step-by-step direction. If you follow those directions precisely, you will do fine.
You have some decisions to make before you decide how to approach the project, because the best way to do it depends on several things:
Did you use the DH “One-click” installer to create your WordPress and, if so, do you need to have the ability to use the “one-click” updater in the future rather than doing it manually in the future?
What version of WordPress are you currently running?
Do you want to use your existing database and/or host, or do you want to create a new database or host for the new location/site?
How comfortable are you with your skills in the areas I described in my opening paragraph?
I’m happy to help you once you have reviewed some of the material I’ve mentioned, and once you have answered the above questions. I’m not trying to make it harder than it is, but those things need to be understood before I can guess which way is the best to accomplish your goal.
At it’s simplest, if you have the understanding and skills, you can simply rename a directory or two, modify a few files, and be good to go. Depending upon the questions I’ve have asked, however, it could entail the creation of a new “one-click” installation in the new domain, the exporting of your current content from the current database, and the importing of that content into the new WordPress installation/database.
I can’t tell you which is “simplest” or “best” till you have reviewed what is involved, indicated your comfort with that, and anwsered the “one-click” installation and upgrade questions.
Edit: Once again, shonky answered while I was typing…the short version of my answer is “what he said!”