If you're upgrading from Windows Vista to Windows 7 it should be a fairly easy install. You can do what's called an in-place upgrade as long you install the same version of Windows 7 as you have of Vista.
For instance, if you have Windows Vista Home premium you can upgrade to Windows 7 Home Premium. You can also go from Vista Business to Windows 7 Professional, and from Vista Ultimate to 7 Ultimate. Any other upgrade, like Vista Home Premium to Windows 7 Professional, will require a clean install. That means you can't just turn Vista into 7. You have to export all your data, erase the hard drive, and then reinstall all your applications and data. A lot of computer experts think you should do a clean install anyway, just to make sure your machine runs better.
See our video for upgrading XP to Windows 7 for that process.