default domain for network conections

scenario: acive directory domain and laptop. normal user on laptop
(administrative rights) manually synchronized with normal (non-admnistrative)
user in ad. both users (ad and laptop) share the same user name and password.
when connecting to a file server that is also a dc for the ad domain, user /
pass on laptop beeing the same as user / pass in domain, authentication works
automatically without requiring the user to enter his credentials.
on any other server (that is not also a dc for the domain) the user is
required to enter his/hers username and password in the form "domain\user" or
"user@domain". i know why this happens, so this is not the issue.
the issue is that i would like very much to be able to set a default domain
for the credentials provided to any server (which btw, are provided everytime
anyway) to be changed, from "username" or "laptopname\username" to
"domainname\username" or "username@domainname".

this is because of practical reasons. like setting an add this domain in
tcp-ip properties for servers that have netbios disabled, so that when i
enter servername, after trying to resolve servername, it also tries
servername.domainname (domainname beeing any domain set in the tcp-ip
property page)

so bottom line, if i would have the same user name and password on my laptop
as in the ad domain, i would like to skip the please enter your username and
password window (WITHOUT saving passwords locally, which is very unsecure)

anybody got any ideas ?