Personally I prefer NTFS. It is reputed as being the more stable and faster of the two file systems (NTFS vs. FAT32). Also, if you have a large HDD like 40 gigs or more, I would recommend partitioning it into around 2 or more 20 gig partitions (depending on HDD size obviously). That way when you do your monthly defrag you can do just one partition (the one you wrote to more, or use more, that particular month) instead of having to do the whole drive at once. Saving you some valueable time. However, the bottom line is that it's up to you.