Never say you're gonna quit or leave, never give a notice, the amount of ppl I see here mentioning they gave a notice is staggering, correct me if I am wrong but there is no law anywhere in North America mandating one to disclose to their management that they are leaving.
Keep it a secret, just leave and give no news. You owe nothing to these folks. In some places they will have to fire you and pay you that 2 weeks anyway.
Makes no sense to me that you would warn them. Do they warn you 2 weeks in advance when they want to get rid of you?
The only instance where I would do that is if those people have been genuinely nice to me, but genuine, nice and work these days don't mix well together.