Pretty sure all of the original is on Instant Watch. I haven't seen any of Korra yet-though I should.
Oh thanks. I'm pretty sure sickVisionz can squeeze in five episodes a day (around 150 minutes/2.5 hours or so). He'll catch up in a week.
I'm the type to lose a lot of interest in checking out any completed series if I find out it's more than 13 episodes long. 50+ is basically a guaranteed not watch. Plus, I saw a few minutes of Avatar on Nick a long time ago and I've got no interest in checking the rest of it out.
@DCypher: Nooo, you reminded me that it exists! I was doing so well to forget about that dark day, but now I remember everything...
On topic its not necessary to watch Avatar: The Last Airbender (I personally got all 3 seasons and watched them before Korra first aired, took me around a week), but it does have plot points that you would not understand fully (At least at first) if you never watched the first series.
I just don't feel Korra the same way I did Aang, I think the way it's shot, the lighting, the atmosphere and the story are great. Totally on par. I just don't feel the same way after a few episodes of Korra that I did when I first watched Avatar. Just my feelings.