SQL Server 2005 Resource Governor ?

Hello is there a way or method along the lines of Resource Governor within a SQL 2005 instance (am aware that that feature began starting with SQL 2008) ?  (One DB app is over-consuming resources slowing down other DBs residing on same SQL Server.)

Also what are the pros & cons & things to be aware of SQL 2008 & up in using Resource Governor ?  Heard that though it was a good new feature idea that it's not all that cracked up to be.

Thanks in advance.