You would think that Windows would let you fall back from NTFS to FAT32, but no...If you want to, the help file says you must reformat to FAT32. Partition Magic, on the other hand, lets you convert from NTFS to FAT32, but the software comes with a price.
I believe there are various freeware utilities on the Internet that lets you convert from NTFS to FAT32, though they are not guaranteed to work and take no responsibilities for screwing up data on your hard disk. Do a search. I am making no recommendations because I also don't want to get blamed for screwing up your data
. Back it up, back it up, and back it up, before you run those programs!
Another workaround if you want to read and write files from NTFS and ext3 filesystems that I find handy, as I am in the same situation you are, is to simply copy files over the network to a Windows 9x share or vice versa.