Abhay,
Even if you have smaller datafiles (say 2GB or less), you have no control over how the blocks/sectors are filled in the hard disk. If there are other files/data on the disk your new files/data bolcks will be scattered around the disk.
Windows disk defragmentaor is a simple example that gives you a visual idea of the data in the disk.

Frankly,I won't be much concerned about disk level frgamentation.