My opinion?
Ubuntu. Of all the linux/unix forums (for help), I think
http://ubuntuforums.org/index.php has the most activity.
New build vs. off-the-shelf shouldn't pose any more problems. I've been in the process of closing the 'Windows' since just before Christmas, but that's with 3 laptops, 2 desktops (1 new build), and a partridge in a pear tree.
Gettin' it online should only take a few minutes post install with a hardwire. Wireless only a little wire longer, although 1 laptop did take me 3 days to configure. And 3 more to do it again, after wipin' the config by doin' a distro upgrade


Ubuntu - that's my opinion.