Just so everyone knows, the "WWW" is site-dependant. I turn off "www" on all my domains, I hate it, and it doesn't mean anything anyway. Seriously,
http://tomshardware.com COULD be a valid webaddress if they set it up to be. Instead, the webserver redirects it to www.tomshardware.com.
In my opinion, the http:// is more important than the www. The http:// specifies the protocol (as opposed to ftp:// for instance, which most web-browsers can understand). On the other hand, www is just a meaningless prefix. You could make it wxy.tomshardware, 123456.tomshardware, toms.tomshardware, etc... It just another piece of the address.
Anyone remember realnames? For a while there, IE was integrating realnames into its addressbar, so typing microsoft would resolve to
http://www.microsoft.com for you (it will anyway if you use Opera or some other browsers). Anyway, realnames died when IE dropped that support, and thus went the world of simple-to-remember domains. Seriously, who wants to remember http: vs. https, or www vs. www2, or .com vs. .net? The whole system is flawed.