IMO...users should always be concerned about malware...when attaching any device not acquired new. If malware can exist on a device, it can be transmitteed by exchanging such devices.
As for attaching an additional drive to a system...there are considerations.
a. Type of system (laptop or desktop).
b. Hard drive connections available on the system.
c. Cables which might be required...for connection to both motherboard and power supply unit.
d. Type of hard drive. Generally, there are two type, SATA and PATA.
A quick look at the graphics Here
(Figures 1, 2, 3) gives an idea of the physical differences regarding connections on each. Although the graphic doesn't show it...the PATA/IDE motherboard connection on a drive...is considerably larger than that used for SATA drives.
The first thing that I would do with any drive which I did not acquire new...would be to delete everything that might reside on that drive. I would delete all existing partitions, if any...after ensuring that my system is well protected from malware.
Edited by hamluis, 11 January 2011 - 12:48 PM.