First thing is ATM/AMD GPU's will work far better than NVidia.  ok, AMD it is...
Oops ATI, but you got what I meant lol

Next with the current difficulty, you're looking at about 3-5 high end pc's to start making a somewhat decent profit. whats decent profit? i need 5 computers? how man cards each pc? 1-5? so maybe 25 cards needed?
I run 2 cards each PC currently

I'm running 4 7970's (soon to be 5), 2 5830's, and a measly 7770. All together I get about 3.4 GH/s which is like 0.22 BTC a day.  whats numbers mean?3.4 GH/s? ghz per scond? of cpu? or total power? im confued....   and o.22 BTC a day, so 5 days=1 BTC?
g=Giga hash per second, the number of solutions to the complex math program that ties into confirming past transactions on the bitcoin network.

The PSU for these rigs 1250+, you will be drawing a bit of power with cards, fans, etc. i bet...

Fans ARE A MUST! My cards run (auto target set) of 75 degrees celsius (167 degrees F) imagine 4 of them blasting in 1 room, it will make the room unbearable unless you have some type of ventilation setup, so you needs fans in the PC to help cool the cards a bit, or send cool air through the system.

need server room ac for all this stuff... thinking my electric bill will go thru roof..Thanks.