Just recently ventured into the USB External drive world with an enclosure that accepts both SATA and PATA :
AcomData Model #: SMBXXXU2E , along with a Seagate 160Gb drive . Went to my trusty Ghost2003 to clone my C: drive ( with 15Gb of data ) only to discover that it was going to take 10-12 HOURS at about 50 Megabyte per MINUTE . Tried using Ghost 2003 from a floppy, and also from a bootable CD ( that was provided a while back from a "Shadowy" character

Either way I was looking at many hours . Also tried going 'around' the USB hub I was using, and connected directly and removed all other USB connections. Not sure why this happened , as I clone my Internal drives with the same software in 10-12 MINUTES ?
Stumbled upon an amazingly simple and Free clone software pgm that cloned my 15Gb of data to the External USB drive in about 20 Minutes...
It's called "xxclone" and avail here :
www.xxclone.com
I'm still tinkering with it, but thus far I say it's a keeper . And the price is right
The pgm is only a 1.14 Mb zip file which runs in the Windows environment .
Efficient, just like the older versions of Ghost...
FWIW : FAQ info on the xxclone.com website mentions that Windows cannot boot from an External USB drive . Don't even think about it ?
Raydeo
" Simplicity is the highest form of Science " - A. Einstein