Windows 7 helps you do more. More work, more play, and more of everything in between. Making every task simpler and every day easier. See for yourself—Get the Release Candidate.
Built on the Windows Vista foundation, Windows 7 will help make users productive anywhere, enhance security and control, and streamline PC management. Deploying Windows Vista today is an important step on the path to get ready for Windows 7. With availability targeted 3 years after the release of Windows Vista, customers with Software Assurance will have access to Windows 7 as soon as it's available.
Windows XP Mode: http://www.microsoft.com/windows/virtual-pc/download.aspx
Summary: Windows XP Mode for Windows 7 makes it easy to install and run your applications for Windows XP directly from your Windows 7-based PC. It utilizes virtualization technology such as Windows Virtual PC to provide a Virtual Windows XP environment for Windows 7. Windows XP Mode provides our Windows 7 Professional, Windows 7 Ultimate and Windows 7 Enterprise customers the flexibility to run many older productivity applications in a virtual Windows XP environment on a Windows 7-based PC.
Beta site: http://www.microsoft.com/windows/virtual-pc/default.aspx
How to set up application virtualization: http://www.microsoft.com/windows/virtual-pc/get-started.aspx