I am with the others. Replace the radiator and probably the expansion tank as well. If you buy from OEMbimmerparts.com, they are in San Antonio and it may come the next day! BMA auto parts from California also arrives in about 2 days with no frieght changes as well. I have been amazed by both of them.
I have coverted two of my BMW's (1999 528 i and 2001 325i) to NPG+ waterless coolant and I believe it will save your engine if you are close to overheating. mbell666 and I are both in Austin and can talk on the phone if you want to PM me.