lalalala, It is always a good idea to backup your players firmware before you do anything to your player. You can do this by downloading s1fwx from
HERE and there is a guide to using s1fwx
HERE.
Then you can upload your firmware to site
HERE for safe keeping.
May I ask why you want to format your player in Fat32? Are you having problems with it? For a 1GB player I would suggest FAT format instead there are no advantages to Fat32 and it does take up slightly more space on your player.
Be aware that if your player has a memory chip that has been hacked so that it reads as much larger than it's true size, formating the player can remove the hack and the chips true size will only be available.