How to search NT user groups?

I have a requirement to be able to take a NT username and do a search to bring back all groups that the user is a member of. Can this be accomplished without using a 3rd party solution?

Any example code or information would be appreciated..

Oh ya, I will also need to put this in an ASP page as well.

Thanks!

BTW, we're not using Active Directory so ADSI will not work.