Artificial nutrition and hydration are forms of life support. The Supreme Court has ruled it's identical to respiratory, cardiac, or renal support.
Let me give a quick synopsis of why Schiavo is not suffering:
We have two basic states that matter; wakefulness and consciousness. You must be awake to be conscious with the notable exception of dream states where varying levels of wakefulness and consciousness exist. Drugs (anesthetics, sedatives, hallucinogens, etc) can also manipulate wake and conscious states.
Schiavo is not in a coma. In a coma, a person lacks wakefulness and consciousness. These people require respiratory support b/c the respiratory center is located in the brainstem . . . same location as neural pathways that regulate wakefulness. They require nutritional/hydration support b/c the ability to feed requires coordinated activity between cranial nerves and the cerebral cortex . . . the cortex is required for consciousness. This means a person in a coma isn't hungry, isn't thirsty, and doesn't feel pain b/c all of those functions REQUIRE processing by the cerebral cortex. A healthy dose of ketamine (dissociative anesthetic) doesn't do anything for pain but you no longer care and won't remember. In essence, a drug induced form of altered consciousness.
Schiavo is in a persistent vegetative state. In PVS, a person has wakefulness (sleep/wake cycles) but lacks consciousness. Accordingly, she sleeps, wakes up, blinks, may even moan but she is not conscious. She lacks the desire and ability to eat b/c she doesn't know she's hungry. The same is true for thirst. In fact, most if not all neuroscientists would say "she" doesn't know "she" exists.
If Schiavo was existing in a minimally conscious state (MCS); ie some tiny shred of evidence she has some degree of consciousness . . . doctors would manage support withdrawal by providing palliative care (ice chips from dry mouth/lips, analgesics for pain, sedatives for sleep). Pain is NEVER a necessary component of death. Further, the organ failure (renal followed by cardiac) that will cause her death doesn't cause pain. Regardless of what Rush believes, OxyContin was never designed to get people high . . . it's an excellent means of controlling pain. A healthy dose of a barbituate (phenobarbital - seizure medication), not only induces sleep but it can suppress respiration enough to hasten death . . . a good physician knows how to cook up a quality palliative care plan.
Another issue is locked-in syndrome. By definition, these people are functionally, if not fully, conscious. They just lack voluntary motor control with the notable exception of eye movements. There's no way a competent neurologist would miss LIS if that's the appropriate diagnosis for Schiavo. The prognosis would still be poor but it would be immoral to end her life by nutritional/hydration support.
I've been very disappointed by the alleged medical professionals that have misrepresented Schiavo's condition, prognosis, and process of her death. I have no expectation that laypersons like DeLay, the Schindlers, the two Bushes, Lou Sheldon) would understand what's going on. But even a mediocre physician should be in the ballpark.
EDIT: Apparently Schiavo's doctors are taking the easy way out. They are giving her morphine. Opiates are very good analgesics and decent sedatives but they do not suppress respiratory drive . . . which means it's very difficult to kill someone with appropriate doses. I'm personally opposed to using opiates instead of barbituates for end of life care but several busy body politicians/AGs and families have been known to prosecute/sue doctors that help people achieve a "peaceful" death.