Need pc gaming advice.

I'm sure there are better forums to present this question but I figure one or two of you fine folks are hardcore pc gamers who can answer a question for me.  

Okay so I'm going to build a gaming PC and have pretty much my whole build finalized but I cannot get a straight answer as to how much GPU juice I should shove into this for my needs.  I'll be running this on a 51 inch 3D television with 1080p res.  Does 3D require me to buy those 5 or 600 dollar vid cards like the gefore 680 or 580?  Or could I get by with maybe two 560 ti's in sli?   Pisses me off cause there are so many different gpu's and configs and they don't explain shit about what you will need for certain functions.   My last PC gaming stint was around 10 years ago so I have no idea now as to what is overkill or if it won't have the power to run smoothly for me.    Plus would it be in my best interest to wait for 3rd gen intel cpu's and 600 series gpu's or would the performance increase vs price be marginal at best? 

Any help on this would be cool folks.  Or if you could point me in the direction of a pc build forum where I won't be treated like a moron is appreciated as well.