SQL Server same versions and limits

SQL Server 2008 Express has a 4 GB limit on database size 
SQL Server 2008 R2 Express has 10 GB.

Windows Server 2008 R2 Evaluation (180 days)

http://www.microsoft.com/downloads/details.aspx?familyid=BA571339-5436-4CF5-9C37-6ED7DAB6F781&displaylang=en