Why submit ? it just needs to have BL and msn makes the job. I never submitted a site to msn and other SE and a few weeks later, the sites appear anyway.
I never had to submit...the site show up after a few days. I put a site in my DP signature last week and it showed up in google's index in 6 hours.
Don't submit your site too many times if you do but it's not necessary. Just get some backlinks and msn's bot will find you and it will help rankings,etc. whereas submitting won't help rankings; it just tells them you're there.
You really don't need to submit your site on search engines. Just build more backlinks and you'll be automatically crawled on this SE's.