Microsoft Press Pass: Legal News Site Source for lots of info on the antitrust actions against microsoft, including a very useful chronology of trial events.

Antitrust.org Source for some more advanced articles on antitrust issues and economics. Not recommended for beginners.

The Center for the Moral Defense of Capitalism Very good site written from the position of the antitrust opponents.

US Department of Justice Antitrust Division Lots of technical court documents and information on antitrust actions of the past. 

The Freedom to Innovate Network Presumably a third party site maintained on Microsoft's server. Lots of opinion pieces in support of Microsoft's advocates.

Anthony D. Becker, Ph.D.'s Antitrust Case Summary Summary and full text resources from all antitrust cases before the supreme court.

Anthony D. Becker, Ph.D.'s Antitrust Statutes Summary and full text resources from the major antitrust legislation throughout history.

Charles E. Mueller's Antitrust Law & Economics Review: Antitrust Glossary A very good glossary of terms relating to the legal and economic issues relating to antitrust.

FindLaw Antitrust Resources An index of antitrust resources.