Not everyone is comfortable with mucking around with 301 redirects and .htaccess files, but redirecting from yourlovelysite.com to www.yourlovelysite.com is pretty darned important (or vice-versa). If your lovely site is a WordPress blog, then you don't ever have to get your hands dirty playing in the 301 cesspool again.
There's a stupid-simple WordPress plugin called Enforce www. Preference that does all the work for you, and it even goes one better...it also will strip off index.php from the ends of URIs.
I just tried it over on my Dazzlindonna blog (because I'd forgotten to deal with the www issue there), and it couldn't have been any easier.
- Upload the plugin.
- Activate it.
See? Stupid simple.
If you've used the www in the url of the Options / General section, it will redirect non-www to www. If you haven't used www in the Options, then it will redirect www to non-www. So it just uses whatever you've already decided upon when you originally installed WordPress.
Sorry this plugin doest exist anymore… “This plugin has been marked as retired. It is recommended that you no longer use it.”