Good choice of OS! However, when it comes to distribution, you may want to consider what You prefer.
When people think Linux, Ubuntu immediately comes to everyones mind.
Ubuntu is not a bad thing, not at all.
However, the desktop choice may not always be the best.
So when picking a Linux distro You may consider the following things:
what desktop environment do you prefer? Unity (Ubuntu specific), Gnome 2 or Gnome 3 (very different experience) or maybe KDE (a lot of bling not unlike Win7).
where on the scale do You find yourself - stabilty or new features? They do not always come hand in hand.
BUT - distros featuring many new features like Ubuntu or Fedora are not to be considered unstable.
However some distro's are really worked on a lot before released, hence showing both less problems and less new cool things.
do you have any preferences concerning package management? there are 2 big ones out there - RMP and DEB. This is maybe not the most important choice, but it may have some influence in the end.
There are more things to consider of course - one of the most important is - does your distro of choice handle your hardware properly?
This is a very important thing to consider.
Fortunately many distros offer live media's to download and test your hardware on before installing.
I would recommend to use Unetbooin to create the Live media's for you. That way you won't have the hassle of getting the ISO's bootable on a USB stick.
Asking me I am using Fedora since a long time. It does not have all the things I want but many enough.
It is stable, can handle my hardware and is pretty fast.
Hope this gave You any more insight to make a sound choice.