Should I inform Grad schools about being accepted to other programs? I applied to several Grad schools and recently got a letter of acceptance from one of them. 
Should I inform the other schools about being accepted? Will it improve my chances with them or just create antagonism?
You should definitely tell any school you no longer want to attend as this will save them a little time. Any school that you would rather attend, you should contact and let them know when you need to make a decision by. Not all grad schools do admissions in an atomic manner. If a higher choice school wants you, they may be able to hurry their decision so as not to lose you.