As we've pointed out several times, the Vikings' finish among the top four teams in the NFL means they are largely removed from the league's free agency process. The Vikings can't sign or even contact an unrestricted free agent until they lose one.

This rule does not apply to street free agents, or guys who were released by their teams, but those players were released for a reason and aren't going to generate the type of interest that the top guys get. Meanwhile, two teams in the NFC North have been busy in the opening day of free agency.

The Chicago Bears are playing host to running back Chester Taylor and defensive end Julius Peppers and both could be members of that organization in the next few hours. Meanwhile, the Bears have agreed to a five-year deal with blocking tight end Brandon Manumaleuna (San Diego), according to Brad Biggs of the Chicago Tribune.

The Detroit Lions also have been very active in trying to improve a franchise that has been one of the NFL's worst. Lions coach Jim Schwartz, the former defensive coordinator for the Titans, reportedly showed up on the doorstep of Tennessee defensive end Kyle Vanden Bosch's home on Thursday night as free agency opened.

Vanden Bosch agreed to a four-year deal with the Lions on Friday that reportedly is worth $26 million, including $10 million in the first year of the contract. The Lions also struck quickly in free agency by signing former Vikings wide receiver Nate Burleson, who reportedly will get $11 million in guarantees.

ESPN reports the Lions also have reached a one-year agreement with backup offensive lineman Jon Jansen.  

In addition, Detroit has worked a trade with Cleveland for defensive tackle Corey Williams. With the Lions holding the second pick in the draft and expected to take either defensive tackle Ndamukong Suh or Gerald McCoy, the Lions figure to have a new look and much improved defensive line.