Well, without going too far off topic, I loved Origins, easily my favourite RPG, and epic in every sense of the word. If you can find the time (as it's totally worth the investment), I'd say finish it if you can, although you don't need to in order to necessarily enjoy DA2. As for DA2, I've just recently finished it off (couldn't hold out for the new patch on PC, as I was dying to play it before the first and second patches for PC came out lol), and it's a great game... it's no Origins, but definitely worth playing, and satisfying in terms of story and development of the overall DA plot.
My advice, since you haven't started playing yet, and considering the number of fixes included in this new TU, would be to wait... if you've held out this long, you owe it to yourself to play the most polished version of the game as you can. Personally, I'd do it simply for some of the quest glitches that you may encounter without the new TU. It's the same advice I gave my brother (who will be playing it on the 360, and hasn't started yet either), and I'm sure he'll be the happier for it.
Hope that helps
