On my wife's computer, her current hard drive is filled with digital junk to such an extent that I am unable to free up enough space to do appropriate cleaning and maintenance. Using Thunderbird, she has years of email and is the recipient of tremendous amounts of incoming e-mail every day. Our default e-mail is a POP account and at times she has tremendous difficulty downloading her e-mail simply because there is not room. OK ... in an effort to relieve the problem, I installed a 2nd large hard drive on her machine and moved a lot of stuff (e.g. pictures,etc.) onto it. Still, the problem remains. I would like to move here Thunderbird itself onto the 2nd drive, along with ALL of her related mail archives. The question is, what is the best way to migrate from one (boot) hard drive (C:) to a second, backup hard drive (call it Z:), removing it completely from C: and thus freeing up an enormous amount of space??