Hi,I am planning to do a fresh install of Windows Vista (Home Premium) and XP with a dual boot. I am aslo planning to do a memory upgrade of my system. The specs of my system as it is now is as follows:Dell XPS 720Intel

I still have to understand how to itransfer the multiple add ons and settings of my flight sim, which is what has been stopping me to do this before.

If you are going to dual boot, your best option will be to install XP clean and apply current updates, then install Vista clean and apply current updates, then install FS9 and/or FSX clean and apply updates, and finally install any addons. Since you have 4GB of RAM I would recommend Vista x64 for FSX.