I need dating advice!??!?

Ok here's the story. I'm really still strung up over my ex. We were together for four years and we still talk about getting back together every once in a while. We broke up because I moved (but now I moved back). My best friend convinced me to join one of those single sites and I met someone. He's really nice, smart (he goes to Yale!), and sweet. However, ever time I try to hook up with someone else my thoughts always turn back to my ex and all the ways they are not as awesome as he was/is (my ex has this way of knowing how I feel or what I think before I even say anything and understands my dorkiness). However, my ex is always busy and consistently indecisive though he thinks in the long run we'll end up together. Should I hold out for my ex or try to get over him?