Question about using WET between 2 HDDs

ok, so far I've got some good answers, here and surfing.
Is it possible (has someone done this!) to use WET to transfer files
(e-mails/ie7 settings/etc) FROM a second NON-boot-in-current-machine xp
harddrive that was running another computer before TO it's current HDD which
would be the first HDD ? Basically, both HDD's in the same machine, Vista
HDD master and old xp HDD slave.
Maybe a rephrase: Old computer, one HDD, running XP. Built new computer,
one new HDD, will run Vista on it. Want to add old computers' HDD to Vista
machine, and use old HDD as a NON-booting second (slave) HDD. Is a succesful
WET after second HDD installation possible to import settings to Vista.
There IS an external usb notebook available and running off old xp computer
available if needed.
Thanks!
Warren