Virtualisation for migration and consolidation isn't always the best answer. I'm not saying it isn't appropriate always, but there are alternatives. One great example which I was asked by a customer last week about was for migrating and consolidating older file servers. The answer could be the Microsoft File Server Migration Toolkit which provides tools and information to simplify the process.
Take a look at the FSMT homepage, the overview whitepaper or the Solution Accelerator for Consolidating and Migrating File and Print Servers