Thanks to everyone here who's been posting on the Fujitsu MPG 3xxxAx issue. My MPG 3204AT failed last Saturday, running fine until it disappeared after a reboot. I replaced it with a new WD 40GB drive and got on with life, but I was curious about the possibility of repairing it. Googling got me to this site, which pointed me to the Flash utility available at the Fujitsu website.
This morning I downloaded the utility, put the old drive back in my system and booted off of the flash floppy. The utility claimed to have recovered the drive and indicated that no firmware update was needed. I just installed the old drive as a slave in another system, and it was recognised during boot. I was able to mount the partitions on it and I'm in the process of copying all my formerly lost data onto a newer HD.
Summary - Fujitsu's Flash utility works on dead drives. Go try it out!