If this is all that you're using jQuery for, I would suggest avoiding any library at all. Just do a simple onload listener or, if you really don't want to wait for that, put the code block at the very end of the body element, right before the closing </body> tag. For what you're trying to do, the DOM will be available at that point. Then, you can call this code, which is entirely DOM-based.
function outsideLinksToNewTab(){
var els = document.getElementsByTagName('a'),
rea = /^http:\/\//i,
for(var i=0; els && i<els.length; i++){
var el = els[i],
href = el.getAttribute('href');
if(href.match(rea) && !href.match(reb)){
el.setAttribute('target', '_blank');
}
}
}
jg