How can I import old Windows Mail messages effectively?

I'm having problems with both my Inbox and Sent Items of Windows Live Mail. I often times need to search by name and also see which messages had attachments.
In the Inbox, all of my imported Windows Mail messages have either a " or a < prefix which is throwing off the search by name option because it not only separates the two versions by prefixes, but also does not list the newer Windows Live Mail messages with these, so there are 3 groups of messages of each name that I have to look for when searching by name. As well, there are no paperclip icons showing attachments in the older, imported messages.
The problem with Sent Items is that all of my imported messages now say that they were sent to me, so there is no true "sent to" information and is impossible to search by name there.
Any thoughts?