Transfer Your Files and Settings Over
If you will use your new Windows 7 machine as your primary computer, you'll probably want to transfer over your personal files and settings. There are third-party applications out there, but you can probably just use the free utility from Microsoft: Windows Easy Transfer.
If you are upgrading a computer to Windows 7, you can use Windows Easy Transfer to gather and store your data on a flash or secondary drive. If you're purchasing a brand new PC, you can do a live transfer over a network or cable.
Windows Easy Transfer is included with Windows Vista by default; simply click Start > All Programs > Accessories > System Tools to run it. If you want to run it on a Windows XP machine, you can download it from Microsoft's site.
You should also consider other files and applications. Double-check for files not stored in the personal folders of Windows. Plus review what software you have installed and make sure that you still have the installation discs or download the information you need.