NO NO NO... Partition Magic aint that easy.
In order to go NTFS back to FAT32, it must first convert to FAT16 and then up to FAT32. That means that the partition can't be more than 2G and you need 500 meg free.
From PowerQuest website:
"When you convert from NTFS to FAT32, the file system will first be converted to FAT16, and then the FAT32 extensions will be added. Whether you are converting from NTFS to FAT16 or to FAT32, you must consider the file system limitations of FAT16. Because FAT16 partitions must be 2 GB or smaller, and because non-NTFS clusters are more wasteful, you must have no more than 1.5 GB of data in the NTFS partition in order to successfully convert to FAT16 or FAT32. When you convert from NTFS to a FAT file system, you go from a high volume, high security, file system that supports file compression, to a simpler, low security file system. In other words, you lose the advantages of NTFS when you perform the conversion. You may receive errors 1680, 1681, and 1687 when performing this conversion. These errors indicate that features of NTFS will be lost."