Since this is going to be an external disk (and not bootable), there will not be any BIOS problems with a large hard disk - so up to at least 500GB should be possible -
the limitation is the partition that fdisk can create.
In fact, Win 98SE can use disks up to 2TB!! - although the block size would be 32K!!
Cameronian, you should read up about Windows 98 (whatever version you have), FAT32 and hard disk sizes before you buy. Check that you have the most recent patches from Microsoft for Fdisk.exe!
Also, any external disk with its own power supply will be backwards compatible with USB 1.1 - it just won't be as quick as it could be on USB 2.0
SD