mount -o remount,ro /dev/hda1 = "busy"

I'm trying to re-mount my filesystem as readonly, BUT it keeps saying its busy.
How do i "un-busy" it

I thought of changing my fstab to mount it as RO... but then i'd never get it back to RW woudl i? lol

You can't make /etc/ readonly without first changing quite a bit of the system. For instance, if /etc is readonly, how is the system supposed to update /etc/mtab to show what you have mounted?

If you really want to go this route though (who am I to argue?), there's a Gentoo wiki entry that shows how to do it with that distribution - it seems pretty generic to Linux (meaning it should pretty much work for yours too). Here: http://gentoo-wiki.com/HOWTO_Read-only_root_filesystem