User credential management – system level vs. application level

Hello,

We are currently using AutoAdminLogon in the registry to get logon to
windows XP embedded, we then launch our application with an entry in the Run
key. We manage security to various features of our application with our own
set of user credentials.

Some users need to have system administration privileges, and other users
should not.

I am looking for advice related to two issues we are having with this
implementation.
1. Switching Windows OS users is slow and causes our application to close
2. We end up with two sets of username/password credentials, one for the OS
and one for our application.

Ideally, we would like to manage logon credentials in one location, allow
quick user switching, and have the same UI application for each user.

All advice is appreciated,

Thank you,
Tony Brown