Yes, Your UK friend answered you right, it doesn't make any difference. But the page rank of your site will be divided between these 2 versions as for search engines consider them as different sites.
If your not happy, you can always redirect.
Originally Posted by SenseiSteve
This question came up on a different forum and one member from the UK said that it didn't matter whether the domain used the www or not, as Google views the www as a subdomain and therefore treats it the same so far as ranking.
I know what my take is on this statement, but I'm curious what your take is?