If you want to play SC2 just cause its the in thing right now, so that you wouldnt sound like some mountain turtle when people around you gush about SC2 ...

I would suggest that you save your money and dont bother.

While the single player portions of the game tries to gently ease you into the brutal world of multiplayer league games, if you have no dedication nor motivation to improve, its not really gonna help much.

Chances are, in this part of the world, I'll give it another 6 months before the random nubs on bnet realise that SC2 on the competitive level is way beyond what they're willing to sacrifice in terms of time and effort.

So please, save yourself the trouble and more importantly, save us the trouble of having to spoon feed you every scrap of information that a simple google search would have sufficed.