Do i need to change my 4870 with a i5 3550?

For one 4870, a i5 is overkill. But for two, You won't lose any performance.

Does it need to be 2x 4870 or i can get a better card with my 4870? ( i'm a noob i know lol)

Another 4870 in crossfire

another 4870 looks like it would cost around $200 so id probbly just go with a new card at that price point.

Yea i think i'll forget the crossfire. I'm reading that it's more hit and miss for games. And with a 4xxx series crossfire, the drivers gonna be hard to find. Thx anyway for the answer

maybe it is hit & miss with 4xxx series, but as of 6xxx series it scales as high as 90+ % in many games...