definately get an MRI. if the tear is intramuscular, you're fucked. but if it's avulsed (torn from the bone), then they can reattach, and you can get a 100% recovery. i tore my hamstring really bad 3 years ago slalom waterskiing, but it was a huge intramuscular tear. to this day, i only have about 60% peak strength compared to my other hamstring. however, i have known people who avulsed their hamstrings from their ischium (the bony attachment at the bottom of the pelvic girdle), and have had a full recovery. all the doc had to do was reattach. avulsions can be reattached for up to 4 years after the injury. after that, the attachment on the muscle side will be reabsorbed, and there will be nothing left to attach. MRI's can look right at the attachment to see whether it's attached, if they can't see anything they can look for calcium chunks in the muscle, indicating where miniscule parts of bone have been ripped from the insertion. this indicates an avulsion as well.