The Boston Globe's Mike Reiss is reporting that the Patriots have signed S Tank Williams to a one year contract.  Williams is versatile in that he can play both safety positions (free and strong) and will likely assume the third or fourth spot on the depth chart at safety.  He's a bit of a downgrade from Eugene Wilson (who he's likely being signed to replace) according to ESPN Scouts Inc., but with Rodney Harrison and James Sanders the projected starters at SS and FS respectively - and Brandon Meriweather and Ray Ventrone also on the roster - all they really need at this point is depth at the position.  Most importantly, Tank will give the Patriots something they have not had in a long time: a big hitter.  Of course, Rodney Harrison is still a tough guy and undoubtedly has a little left in the tank, but the biggest hitter the Patriots had last year bolted to Philly.  You can rest assured that Tank Williams will lay some huge hits next year on unfortunate opponents.