I've been playing piano for seven years, and I have to say, I'm pretty darn good. Will it be easier to play guitar now than If I had started playing guitar with no musical experience whatsoever? I also heard that people that play piano can't play the guitar well.
It should make your fingers more nimble than the other novice guitar player, as long as you realize that you are not just going back and forth on the guitar, as you might on a keyboard. You have to go up and down on strings, too. Also, on a piano, you can play multiple notes in a linear style. On a guitar, only the nearest fret is heard on a string.
As long as you are comfortable with that, go for it. Many piano players don't play guitar well because of this. ( It also goes vice versa. I can't play piano at all because I get it in my head that only the highest note will be heard.)