Ubuntu, without a doubt; installs in less than 1 hour, works right out the box. Lots of specific apps. A tremendous community to support you.
I gave up on Gentoo ... I had to get that box running. However, Gentoo has probably more power, good if you have the time to tinker - sorry, optimize :-).
You can try Ubuntu with the live CD, does not install anything on your disk.
I've been running Gentoo on my laptops for about 5 years (before they were versioned by year). First on a Sony VAIO, and now on an Averatec 1050. I can second the "I had to get that box running" sentiment. Compiling everything is a very mixed blessing. A lot of the time, I enjoy the hassles that come along with running bleeding-edge software, and it's a great learning experience. Plus, it's nice that nearly all of the programs I find online are included in at least some state in Gentoo.
But, about two weeks ago I had yet another "Oh, no! I upgraded everything and something broke" experience. After I upgraded the X.Org server, the i810 video driver wasn't working right (flickering), and I had to drop down to the VESA driver. The upside is that it's already been fixed.
So, if you want to learn more about how compiling works, and you can afford a bit of downtime on a regular basis, or can manage to upgrade only at times when you won't desperately need your laptop, go for it.
I'll also mention that I tend to find more support for the problems I encounter in Gentoo on the Ubuntu forums. And, if you're intimidated by developers' lack of patience/tact, Ubuntu again gets the nod. Nonetheless, it'll be a long time before I switch to another Linux distro (might switch to a *BSD, though). Gentoo is very powerful.