c'est ici http://www.microsoft.com/downloads/details.aspx?familyid=85CFE4C9-34DE-477C-B5CA-75EDAE3D57C5&displaylang=en
This software is for evaluation and testing purposes. Evaluating any version of Windows Server 2008 R2 Beta software does not require product activation or entering a product key. Any edition of Windows Server 2008 R2 Beta may be installed without activation and evaluated for an initial 30 days. If you need more time to evaluate Windows Server 2008 R2 Beta, the initial 30 day evaluation can be extended to August 1st (at which time the OS will become inoperable) by entering the product key below for your selected edition.
Windows Server 2008 R2 Beta Product Keys for EvaluationWindows Server 2008 R2 Beta Enterprise (7000.0.081212-1400_server_en-us-GB1SXFRE_EN_DVD.iso)