No, IDE and USB are not identical, especially if talking USB 1.1, which has been quite troublesome and very limited.
USB 2.0 holds promise, but according to some KNOWLEDGABLE sources, still falls short of an IDE drive when it comes to high speed data transfer.
http://www.extremetech.com/article2/...52431%2C00.asp
I'm getting one along with Norton Clone for back up purposes, but not until I replace USB 1.1 with 2.0. I believe the jury is still out as far as making USB the primary operating drive.
George