Yeah sections of the ram are reserved for the kernel and ramdisk to be uppacked into, the radio, wifi, camera all have ram dedicated that the user cannot access. After all it is set aside, your left with about 350 MB.
As for the internal storage, its a 2gb integral card, so formatted its about 1.8gb or so. Then take away 250+MB got the system partition, 180mb for the cache partition and the rest for various other system partitions and your left with a little over a gig of space on the /data partition which is where the apps are installed to. Hope this helps clear everything up!