Can I force this Lacie firewire drive to format as FAT32?
Partition Magic is your best bet, but it costs money. I don’t think the Windows 98 boot disk supports firewire, and magick’s suggestion won’t work either (it’ll crap out after pretending to format your disk for a good hour or so). If you want something that will work for free, try booting up using a Knoppix live CD and then running QTParted, the free Linux Partition Magic clone.