I get the error:
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51
I just got my Arduino Duemilanove ATMEGA 328 today and it was working just a few minutes ago (well I sometimes takes a few tries to upload the program). I selected the right board and serial port, I am running Vista 64bit.