Please note that an inplace upgrade to SRM 5.0 is only supported from version 4.1!
If you're running on an older version such as 1.x you will need to follow a few steps to get to the current version including an upgrade first to 4.1.
Michael White did a fantastic job of documenting the 4.1 upgrade process in July 2010 and if you're looking at moving to 5.0 from an older version you should consider his material mandatory reading before upgrading to 4.1. 🙂
Take a look at Michael's upgrade material here: