I had a friend in college who was addicted to an MMO - not quite at the hours you describe, but not far off. Every semester when finals came around, we tried to tear him away from his computer and help him study, but he never listened. When convincing/arguing/pleading failed (and eventually, it always failed), we would hide or break his game CDs, but he would buy, pirate, borrow, or otherwise find a new copy. He failed out of school.

Seek professional help. Talk to the counselors at your school.