The Vikings signed their remaining unsigned draft picks Wednesday.  The 3 are 2nd round safety Tyrell Johnson, 5th round quarterback John David Booty, and 6th round center John Sullivan.  Both Booty and Sullivan signed 4-year contracts.  The Vikings have begun reporting to training in Mankato already and begin practice Friday.  The players arriving yesterday were asked about the potential of Brett Favre wearing purple. Cornerback Antoine Winfield said if it happens it would be "a great move for us."  Head coach Brad Childress refused to comment on the speculation.  The Vikings officially open camp Friday.