Art, I have used external eeproms on most all of my projects and have never had any problems with bad data. I just make sure I dont have any interrupts during the write cycle and always use 2.2k resistors for the pullups. I am currently using 2 x 24LC1025's for about a months worth of data storage on a solar telemetery project and haven't had a bad bit all summer or winter. So far its been -5 degrees a couple of nights here.. I would suggest maybe using 2.2k resistors for the pullups and the I2C_SLOW command. I also never use more than 6 milliseconds of delay after the write... Good Luck...

Dave Purola,
N8NTA