Windows 7 in enterprise - What about the account picture?

We are about to deploy Windows 7 in an enterprise environment and I am having some concerns concerning the account picture that is displayed on the logging screen, and in the upper right corner in the start menu :

How do you guys deal with this picture in an enterprise environment? Because I guess that my users will waste some time trying to change this picture, and try uploading their own picture, which is not what we want in a professionnal workspace. And if we deny users to change that image, maybe some people will be mad about the picture that have been permanently randomized for their account.

So is there a way to replace every account picture with a dummy logo of the corporation, or maybe do you have a better idea?

Like most things you want to control company-wide, look into using Group Policy.

Specifically:

Computer Settings-> Policies-> Administrative Templates-> Control Panel-> User Accounts-> Apply the default logon picture to all users

Blurb:

This policy setting allows an administrator to standardize the logon pictures for all users on a system to the default user picture. One application for this policy setting is to standardize the logon pictures to a company logo.

...

If you enable this policy setting, the default user logon picture will display for all users on the system with no customization allowed.

There's more info (like picture-file locations, etc.) provided in the full description of that actual policy.

Related SU question: Change user account picture

You can apply a GPO that will force the use of the default picture. The policy is under Computer Configuration, Administrative Templates, Control Panel, User Accounts, Apply the default user logon picture to all users. You could also replace the default picture, which is under C:\ProgramData\Microsoft\User Account Pictures\. The picture must be in bmp format and 128 by 128 pixels.

I think the best solution however is to allow your employees to change it. Customization makes the user feel better. Maybe post a tutorial explaining all of the dumb little customization things your users will want to do so they can do this efficiently.

If your employees waste time, that's their manager's problem. Don't try to solve people problems with technology.