Cowboys RB DeMarco Murray says he's "ahead of schedule" in his rehab from this past December's broken ankle.  "I've been working hard to strengthen my ankle," Murray said this past week. "I'm definitely ahead of schedule. I think I start running on [Feb. 6] actually, so I'm excited to get back there."  Murray may be limited in OTAs, but he should be a full-go for training camp.  He'll enter the 2012 season as Dallas' lead back, although durability remains a concern.