Linkbuilding - Difference between http://www.site.com and http://site.com?

I was just wondering, before I dish out too much money on linkbuilding, if there is any difference between http://www.site.com and http://site.com?

I notice yahoo has my site indexed on the front page as http://site.com. If I get a bunch of backlinks to http://www.site.com, will those backlinks count?

Thanks for any info.

Google sees http://www.site.com and http://site.com as different sites. Actually you cand have different sites.

On my sites I've put a 301 redirection from http://www.site.com to http://site.com.

Is there a difference between redirecting the www to the non-www or vice versa?


RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]

Like will that be different SEO-wise from doing it the other way around?

Thanks.

I was checking the google webmaster tools the other day and it seems you can nofity google to use either


or to decide itself so i now i am still unsure if it makes a difference.