How to get all sites where the user is a member.

Hi

I am trying to retrieve all the sites[including subsites] in a site
collection that a user has permissions to view. Is there an API call/web
service to retrieve the information easily?

I checked the SPWeb.GetAllSubWebs() , but if the user does not have access
to the Web, but has direct access to its subwebs, how do I get the
information.

for (e.g) SiteA[User does not have access] has 1 subsite Site A1[user has
access]. in such cases how to retrieve the information?

Thanks a lot for your assistance.

I am using MOSS 2007.

Sai