I presented a TechNet evening on the 28 Feb - 'How do I migrate from my existing SQL server and what are my options?' As I only had two hours my aim was to highlight the procedure for upgrading or migrating. In particular the need for planning prior to moving the different components.
To aid in your planning there is the Microsoft SQL server upgrade advisor It analyzes instances of SQL server 7 and SQL server 2000 in preperation for upgrading to SQL server 2005. Upgrade advisor identifies feature and configuration changes that might affect your upgrade, and it provides links to documentation that describes each identified issue and how to resolve it. The advisor is rules based so will not cover every issue but will generate a report to allow you to take action before, during and post upgrade.
There is a resource centre for upgrading and migration which includes white papers and a link to download the upgrade advisor tool. http://www.microsoft.com/sql/solutions/upgrade/default.mspx