im using my old laptops IDE HDD with my desktop via USB.my Q is..should i always use the "Safely Remove Hardware" option when i shutdown my PC?
becouse i would like to keep it plugged in all the time.
No - no need. Windows takes care of all that while shutting down. Some times back i also used HDDs via USB without any prob. Only take care while switching off the HDD. Also switch off the HDD after ur comp shuts down.