Macs can read and write to Fat32 windows drives for sure. FAT32 is used for most external devices like cameras.
OS X says it can read NTFS drives but probably won't write to them or at least can't guarantee it will write safely. NTFS is the default drive system for Windows2000 and XP.
Glad to hear it shouldn't be a problem. It took me AGES to load my CDs on to the drive in a really good form and it would be very depressing to lose them/have to work really hard to tranfer them.