AvoK95 wrotemy power supply is getting shipped tomorrow so time for a graphics card :D
i am considering getting the Asus GTX 560Ti ...i don't need anything better because i am not a hardcore gamer , i only like decent graphics and some FPS.
if in due time my system starts to lag i will consider getting a seconds card like a 550 or another 560
You cannot SLI 560 with 550. Second thing, by the time such a high-midrange / low high-end card starts to lag, cards that far outstrip the card's potential for little money will be available. By then, SLI would sound like a power-hungry, low value, feature-deprived idea. New cards have newer features. Old cards consume more power. My advice is: either SLI immediately or at max after 1 year or forget about it and wait for something better.
There's micro-stuttering to consider, also. Look it up. It would definitely drive me nuts. SLI does not scale theoretically (2x), max usually is 1.8x and rarely 1.9x.