Report Builder button

We've installed SQLServer 2005 and are trying to use Report Builder. But we only see the Report Builder button if we're currently logged onto the machine that's running RS.
My understanding is that anybody with a role of Content Manager should be able to see this, but nothing we do with the role assignments seems to help.
We've installed on XP and Win2003 machines and this behavior is consistent.
Any ideas?
TIA,
Jim

This is a quote from BOL:

"The System User role is a predefined role that includes tasks that allow users to view basic information about the report server. It also includes support for loading a report in Report Builder. Report Builder is a client application that can process a report independently of a report server. The "Execute report definitions" task is intended for use with Report Builder. If you are not using Reporting Builder, you can remove this task from the System User role. The following table lists tasks that are included in the System User role definition. "

In my case, to let a user launch ReportBuilder from the Report Manager web interface, I had to add the user to Server Properties\Permissions page (from Management Studio) and checked the System User role.

Leonid.