Usually, upgrading the HDD to a faster HDD is not a huge performance gain, but if you have the 250GB Fujitsu in yours, a faster HDD will make an impressive difference as that 250 is sloooooooooooooooooow. It's one of the slowest hard drives on tests that examine literally hundreds of modern drives.
I am all about the WD Scorpio and Caviar Black; a 7500 RPM Black series is quiet, reliable, energy efficiency, and about as fast as a reasonably priced HDD can get. Of course, even the cheapest SSDs will blow the best enterprise grade hard drives away in both speed and reliability, but their costs limit their usefulness to users needing over 256GB of internal storage.