A nice easy way to copy mail from outlook express to Outlook and vice versa is to first create some folders to manage the mail. Then open Outlook Express .... copy the files to the relevant folders using drag and drop. Once completed open Outlook and then drag and drop back into the relevant folders created in Outlook.
As Qdos & ccatlett1984 says you can have multiple accounts set up with no problem. And just use filtering/rules to put the mail in the correct folders automatically as they come in.
And when sending mail you can choose which account to send it from.
By default if you reply to a message that was sent to eg.
fred@home.com the message will be sent from the account
fred@home.com and the same would happen for
fred@work.com etc. although if you wanted you could change this to be sent from the account of your choice. But you don't need exchange for this. (image 4)