For those considering migration to the next versions of Windows (client and server) there are a lot of free resources from Microsoft available to help you.

Microsoft Assessment and Planning Toolkit Solution Accelerator (MAP)- allow you to scan the devices on your network (using agentless technology) to gather a detailed inventory of the computer. The resulting report will identify what computers can run Windows Vista, Office 2007, and Application virtualization technology. Hardware and driver updates are also recommended per machine in the report. Windows Server can also be assessed for compatibility with Windows Server 2008. If you are looking at data center consolidation, this toolkit will also provide guidance on what servers could be consolidated onto a Windows Hyper-V host.

Microsoft Deployment - is the fourth generation deployment accelerator. It provide a proven methodology, guidance, and tools to help you automate the deployment of Windows XP/Vista, and Office 2007, Windows Server. Using this toolkit you can create "lite-touch" or "zero-touch" deployments for your organization. this should be used after the assessment and planning is complete.

Active Directory Migration Tool (ADMT) - If you are migrating to Active Directory from another Directory Services, or you are consolidating domains in separate forests, you want to use this tool. ADMT simplifies the process of migrating objects in AD. you can migrate users, groups, computers among other features.

Password Export Server - this tool lets you migrate passwords, when performing accounts migrations between different Active Directory environments.

Application Compatibility resources for Windows vista - along with checking your hardware and drivers for vista compatibility using the MAP, you also need to test your applications to make sure they will run under vista. Here are the primary resources for application compatibility.