over 121 gb

Serial ATA drives perform better than the equivelant Parralel ATA drive from the same manufacturer. If you're current system doesnt have SATA support on board you can easily get a controller card for a decent price to add this capability to you're current desktop.

I have noticed a very significant speed increase in raw data rates when put head to head with PATA drives and this Western Digital drive is a very solid performer. In addition to the speed increase over Parallel, you also have the ability to mount more than 2 drives (master, slave) to each controller enabling you're system to have as many as 16 drives per controller, you can also add multiple controllers so you're limiting factor is the case the system is mounted in. With 250GB per spindle, were talkin about storage in the range of 4 Terabytes in a non-RAID configuration (Redunt Array of Independant Disks). With RAID5 you gain some degree of fault tolerance, which is the ability to lose one drive per controller without losing data.

As a single drive replacement for existing parallel ATA, this will prove itself quite worthy in most any system. If it is an add in drive, you should consider migrating the operating system to it for speed and use the slower existing drives to offload storage.