I believe that it can read and write FAT volumes and only read NTFS volumes. I think you can only have FAT volumes that are 32 GB or smaller, though.
If you're trying to put a drive in to get files off of then you should be fine. If you're trying to make this a working hard drive in a Mac then you should probably copy the data off and re-format it in a Mac standard.
If you're simply talking about accessing a PC from a Mac over a network then none of this mattes at all. In that case it's Windows that is accessing the file and passing it off to OS X. None of these rules matter in that case.
Just to add to Jeff's answer, your Mac can only write files to a FAT32 HD that are 4 Gbytes or less in size. So if you're thinking of copying video files over to the FAT32 HD just break them up into pieces less than the 4 gig limit.