It should.. Ironically I actually just switched my mail from outlook express to Outlook 2003 about a month ago at work, and did the same to my boss' machine on monday. Mostly because of the built in spam filtering system as it has become a major problem (My boss gets about 200 spam emails a day, ranging from increasing his penis, to being saved by God. At least they don't discriminate).
As a side note. The spam filtering is what I like about Win Live mail. You dont have to go through all that, right clicking to empty the folder. There is a small "X" that comes up next to the mail folders that instantly deletes all the mails in it (if you have told it to disable the warnings that is)
Outlook 2003 took about 20 min to import, but it did it flawlessly. Once I was sure everything was fine. I un-installed OE, But for some reason even with it un-installed, Sending mail via a weblink, still opens up OE, which shouldn't be there. So I am still working on that little problem
As to importing into windows live, I just double checked and it was pretty much,File > Import > Outlook Express 6 > Select the folder (which was a duplicate copy of all the existing DBX files) and let Live do the rest.
I've pretty sure you have shut down everything though and made sure nothing else is running, though as a thought, make sure you have windows messenger shut down as well just in case. It has a habit of starting up on its own and it does run along side OE which of course you dont have in W7,............... though I cant think of anything else
