Hi,

There are several ways:

1)if you are using IIS5.1 you can change the user that is impersonate on the
webservice, you can go to the machine.config file and remove the default
ASPNET user, this has some implications related to security, because it will
change the default user for all your sites on the server. (This is not the
account that the client will use, that is a different layer and will still
use IUSR_MachineName). If you want to do it per website you can paste that
code on your web.config file (note: I haven't tried this, I know that some
properties can be set on the web.config but others are ignored and read it
from machine.config, check the help for this)

2)If you are using IIS6 you can easily change that on the website
properties, so its per website, same behaviour as above.

3)If you are going to impersonate remember that only works on Wind2K3 and
XP, for Win2K you need to change the policy settings in order to do this
opening a whole on the security environment.

I prefer the option 1 cause I have more control, but check your requirements
and choose your best approach.

Best regards
Salva