Fantasy football question?

I have Willie Parker and I'm wondering if now is the time to dump him. He's been disappointing. I've been thinking of picking up Justin Fargas. I also have Kevin Walter and he's been disappointing as well. I was expecting a bigger year out of him. I'm thinking of dropping him as well. Even though Pittsburgh is on a bye, I'm thinking of trying to pick up Mike Wallace. What do you think of these players? Thanks for your input.