XP Mode's Ready to Go
Windows 7 XP Mode requires a CPU that is capable of hardware virtualization. You also need to have Windows 7 Professional, Ultimate or Enterprise edition.
To check whether a CPU can support hardware virtualization, users can download, install and run either the Intel Processor Identification Utility or the AMD Virtualization Compatibility Check Utility.
Here's what Microsoft said in their announcement about XP Mode:
Windows XP Mode is designed to provide small business and mid-sized businesses running Windows 7 Professional (or higher) the ability to run Windows XP productivity applications that may not be natively compatible with Windows 7. We expect many Windows XP applications to be compatible Windows 7 however Windows XP Mode is meant to serve as an added safety net so small and mid-sized businesses can migrate and run Windows 7 without any road blocks. Windows 7 Professional is designed to meet the needs of small and mid-sized businesses.