i have a ide dvd writer,but i want to use it as an external usb dvd writer so that i can use it with my netbook too,how can i do that
You could buy an external enclosure for your DVD burner and mount the internal DVD burner in the external enclosure, but it might be easier and not much more expensive to just buy a new external DVD burner.
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An inexpensive USB/IDE/Sata adapter often does the trick also. Unfortunately not all internal drives work with such adapters. LG drives are extremely picky here.