Here's my real contribution to improving the method in the previous hint. (Control Panel » Administration Tools » Computer Management » Disk Management.) Finally, use a Windows machine to reformat the remaining VOLUME you formatted to FAT32 to NTFS instead. Then, after step seven in the first hint, insert a similar-looking step - put 2s3 at end of command instead. To add NTFS to the mix from the previous hint, in the first step, just divide things up into three parts instead of two. If needed, print this hint, and then go to the above link for more help (and there's another link further down that may be of some help).

In this hint, I'll explain how to add NTFS to the mix, and note some significant improvements upon the previous hint's awesome efforts.

This hint (from way back in 2003) is still the best I have come across in terms of explaining how to partition HFS+ and FAT32 on the same external hard drive.