Replacing that 2TB mechanical hard drive with an external SSD is only justified if you're using it as a fast external storage device. For example, if you're using this storage in a PS3 or Xbox 360, replacing the external mechanical drive with an SSD is worthwhile. You'll definitely notice a dramatic decrease in loading times. Of course, it won't match the read speed of the motherboard's integrated SATA, but it will greatly improve game loading times. In cases like this, it's the only justifiable upgrade. But if you're only using it to store information and access it at specific times, your current setup is more than adequate.