Which would better increase my PR?

1) Having my username on a forum as Gayble (for example)

or

2) Having my username on a forum as Gayble.com (for example)

Which out of the two of these would work better at increasing my PR or increasing the likeliness to getting listed on a search engine? I'm all about doing what I can to get PR, I've never had PR1 ever even though I do promote my site and I do exchange links with others.. maybe I'm just unlucky when it comes to PR..