Alternatively create a free gmail account. Create an IMAP account in Windows Mail. Then copy paste all your email from the inbox in Windows Mail into the gmail folder in Windows Mail. This will update the web interface automatically. Will take some time but I mananged in excess of 3000 mails in about two hours. Doing them in batches.
Then you can get them all back into Comcast using
http://secure5.trueswitch dot com