SQL 2005 R2 is a separate version, it's not a patch.
You need to purchase a licence, download the full installation media and run an upgrade.
What you're trying to do is the equivalent of applying a SQL 2008 patch to SQL 2005, it's not going to work.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability