Only Adalius Thomas was a real big marquee deal, and he hasn't contributed to a Super Bowl win. Rosey Colvin was a lesser big deal at the time. The other big signings in hindsight were shots in the dark really that turned out better than expected: Vrabel and Harrison. Pittsburgh had little interest in retaining Vrabel, and SD thought Harrison was done.
So these are the players that were signed as free agents in the Super Bowl years. Some good players to be sure, and some duds, but besides Colvin there isn't a splashy deal among them:
2001: Je'rod Cherry, Mike Compton, Mark Edwards, Damon Huard, Larry Izzo, Marty Moore, David Patten, Roman Phifer, Anthony Pleasant, Antowain Smith, Chris Sullivan, Mike Vrabel, Ken Walter, Bryan Cox, Torrance Small, Charles Johnson, Bert Emmanuel, Fred Coleman, Curtis Jackson, Ben Kelly, Terrell Buckley, Riddick Parker
2003: Chris Akins, Larry Centers, Rosevelt Colvin, Don Davis, Brandon Gorin, Rodney Harrison, Russ Hochstein, Sean McDermott, Ty Poole, Dedric Ward, Mike Cloud, Fred McCrary, JJ Stokes, Aric Morris2004: Josh Miller, Keith Traylor, Rabih Abdullah, Jed Weaver, Kevin Kaspar, Randall Gay, Earthwind Moreland, Hank Poteat