IIS 401.2 Error, Integrated Authentication Company Intranet

Greetings,
This problem may be more of an annoyance than a show stopper, but it does eat network and server bandwidth and causes a lot of useless data to be placed in log files.  I have several ASP.NET sites running IIS 5.0 on Windows Server for internal company usage.  I manage rights through Integrated Authentication and Active Directory.  My problem is that each and every time a page or script is accessed, IE 7 attempts to open the page anonymously, causing a 401.2 error back to the browser, which then tries (successfully) Windows Authentication credentials.  ***The user never sees 401.2, but the activity is nonetheless happening thousands of times per day***.   Is there any way to solve this on the IIS side (I'm assuming NO) so that all requests come with credentials only?  If not, is there any way to configure the user's IE 7 browser to default to presenting active directory credentials first, rather than always defaulting to anonymous and waiting for the credential request?

See log file sample below...

Thanks!

2008-07-22 15:58:23 W3SVC1 GET /EscalationManager/efpstyle.css - 80 - 10.0.2.7 401 2 2148074254
2008-07-22 15:58:23 W3SVC1 GET /EscalationManager/EFP_LOGO.bmp - 80 - 10.0.2.7 401 2 2148074254
2008-07-22 15:58:23 W3SVC1 GET /EscalationManager/efpstyle.css - 80 EFP\dwechter 10.0.2.7 200 0 0
2008-07-22 15:58:23 W3SVC1 GET /EscalationManager/EFP_LOGO.bmp - 80 EFP\dwechter 10.0.2.7 200 0 0