Error: Flight Simulator X Requires XP SP2

When I insert disc 1 to install FSX the Install Shield starts then I get the following message; Flight Simulator X Requires XP SP2.

As far as I am aware I have the latest version so what am I doing wrong?

ANy help would be much appreciated.

Are you sure you have SP2?
A simple way to check it is to right click in My Computer and then Click Properties.

Go to Start -> Run... and type in WinVer then press ok.

You'll notice the second line should say Version 5.1 (some stuff here) and in the "Some stuff here" at the end you should see "Service Pack 2." If you don't see Service Pack 2 anywhere, then you don't actually have it installed and may just have SP1.

If you don't then go to http://www.microsoft.com/windowsxp/sp2/default.mspx and download then install it.

If you do, then you may have a corrupted Windows installation and will need to either do a detect/repair on it or reinstall.