screw the elitist fags who are
>>2, >>3 and
>>4
your basic common sense would seem to be correct, and here is why it isn't necessarily.
there are two basic types of partitioning situations, those that require you to resize partitions and those that don't.
if you do not have to resize partitions, your existing partitions aren't touched at all, and you don't have to worry about them if you add a new partition.
if you do have to resize partitions, yes, it would make sense that to be safest, you should defrag first. however, most defrag utilites don't necessarily put all the files at the start of the partition. so i would back up all data first and try to be sure your power won't be interrupted during the resize.