SP1 HELP

hey all, i installed SP1 for fsx without uninstalling fsx. should i have?
anyway, now when i hit f10 to go to the 2D cockpit the game crashes. i guess il have to uninstall and reinstall the game. i have tried reading some tutorials on the site but i don't quite understand, what is RTM? what is defrag and how do i get fsx working again?
many thanks
anyway, now when i hit f10 to go to the 2D cockpit the game crashes. i guess il have to uninstall and reinstall the game. i have tried reading some tutorials on the site but i don't quite understand, what is RTM? what is defrag and how do i get fsx working again?
many thanks