May 05, 2011 (Standard, Enterprise, Datacenter.etc) license with Software Assurance that permits a Downgradeable License for Windows Server 2003 R2. 
As far as an ISO, that is the only version that comes free with your purchase of the license with Software Assurance if you visit the Volume License Service Center page. One piece batch kusonime.
Windows 2003 R2 Sp2 Iso Download
Windows 2003 R2 Enterprise Iso
Hi, I wanted to make a checksum-identical ISO as MSDN one for MS Windows 2003 Enterprise Server R2 SP2 VLK (POLISH) and since I have been only able to lay may hands on: • English Enterprise R2 Retail SP2 • English Enterprise R2 VLK SP2 • Polish Enterprise VLK SP0 • Polish Enterprise R2 Retail SP2 MSDN ISOs I decided to try making such image on my own. And there is the thing. After comparing EN VLK and EN Retail images the only difference is in these files: I tried to use files from Polish SP0 version but quickly realised that even if I did everything right: I used cdimage to make ISO 'cdimage.exe -lCRMEVOL_PL -t,12:00:00 -n -xx -o -bboot.img CRMEVOL_PL CRMEVOL_PL.ISO' The size was right but checksum different.