Should I pull the trigger?

[splashpot]

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I'm looking at external harddrives that work through a usb port. It seems like a better deal then installing a new harddrive in a notebook. Any one have experience doing this?

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I already bought a new external 7200rpm 250GB harddrive. But my understanding is that the internal harddrive speed is more important. Because the OS and other applications will be on the internal drive.