Probably my laptop. Its hard drive is so damned slow compared to my PC, it just feels horrible to use. And my PC has all my data on it, so I don't really need the laptop for much of anything, except when my desktop decides to have problems, like last semester when a bulging cap disabled my PC.
PC: 4 x 7200rpm drives in RAID 5 = excellent seek times, and amazing read speeds
Laptop: 1 x 5400rpm drive (maybe 4200rpm, I don't remember) = painfully slow seek times, and sluggish read speeds