URGENT...PLEASE HELP!!

Ok yesterday I come home from a prior engagement. Nothing wrong so far. I put the car in the garage. Again, so far so good, everything is perfect. Then a few minutes later I get the munchies and decide to go out for a burger..low and behold as i put my car in reverse I hear an AWFULL screething noise comming from all 4 tires!!....this noise is worse than hearing somebody scartch a blackboard!!...ok now i know it's my break pads seeing as how I havnt changed them in 45,500 miles and i've had the car for 3 years. My question is, since my pads are worn, are there any suggestions any of you can make as to what break pads are better than stocka nd are very reliable. Im leaning towards AEM or Bspec. Any suggestions will be very appreciated. Oh and one more thing, my car was so loud from screacthing that I EVERYBODY was staring and givin me the look like my car was about to blow..hehehe...but i seriously hope it is my break pads because I had absolutly no indication that they were worn. The sound happened so suddenly. In my experiance, I usually hear a light sqeaking sound to tell my its time to change. In this case, it happened suddenly. And its just my luck that all shops are closed today so I'll have to take the day off work on Monday to take care of this problem. Again, any help would be greatly appreciated. Thanks in advance.