Anyone who is considering upgrading to Windows 7, be aware that upgrading from a current Windows Operating System is very limited. Only certain versions of Vista can be inline upgraded to Windows 7, the rest require a custom install, which means a clean installation.
If you are staying with the same flavour of Windows, then this won’t be an issue. You can upgrade from Vista Home (basic or premium) to Windows 7 Home, or from Vista Business to Professional. However, you can’t go from a Home version to the Professional version of 7.
You can upgrade any version to Windows 7 Ultimate, if you are willing to shell out the extra for the Ultimate version.
If you are wanting to upgrade from XP to Windows 7, you are going to have to go for a clean install 
. There are tools to make it a little easier though.
I highly recommend using the Windows 7 Easy Transfer Tool when doing a custom upgrade (clean install). It will make copies of all your user accpunts, save all your documents and settings for your programs and make it very easy to import into the new install of Windows. You will still need to install all your programs again, but for the most part, all your old settings will still be there. The transfer tool also gives you a report of everything transferred, and also gives a list of programs you will want to install (from the list of program settings it saves). The Transfer Tool makes the upgrade process a lot easier.
