Tomorrow is the D-day when Microsoft will be releasing Windows 7 RTM to TechNet and MSDN subscribers among other people.

Windows XP users will not be able to directly upgrade to Windows 7 and they will require to perform a fresh install which will mean that all the applications will be wiped out and you will need to reinstall everything from scratch on Windows 7.

Nirmal from Life Rocks has written a excellent upgrade path for Windows XP users to Windows 7 that will help you backup all your user settings and data to a  external drive and then restore them back on the new Windows 7 installation.

Also most of Windows Vista users will be easily be able to upgrade to Windows 7, so you can download the ISO and burn it to a DVD and then install it on Windows Vista without losing your settings.

To check if your PC is ready to be upgraded to Windows 7 or requires a fresh install you can download the Windows 7 Upgrade advisor.