Upgrading to Windows 7 is easy! Just follow this chart (via All things D):

Basically if it’s green then you can easily upgrade without altering your files (similar to a Mac OS X standard upgrade) and if it’s blue then you cannot easily upgrade over your files (think of it as Mac OS X archive and install option). If you want to have 2 interfaces (Arabic and English) then your only legal option is to buy the $330 Windows 7 Ultimate.

By the way if you did buy a Windows Vista based machine after a specific date you are eligible for a free/cheap upgrade to Windows7 and it’s valid in Saudi Arabia as well.