you have to add the lines to you /etc/fstab...not the lines you have wrote at terminal but something along the lines of:
/dev/hda1 /mnt/windows_c vfat defaults 0 0
where i have wrote defaults, you can look into what different values you can type in there:
for example i don't use the word defaults for one of my fat drives
user, rw, exec, uid=500
so you can see what you actually want to put there.
and just for you know...
defaults is the equivalent to rw, suid, dev, exec, auto, nouser, and async.