We do not foresee any performance issues with the web site load you specified. Of course, the overall performance of the site will depend on the nature of your content. However, you can always use ASP.NET caching to help with the performance.
Our Stress tests on a dual CPU P4 single machine show failure at around 150,000 page views per hour when the output cache is off. With output cache ON, the same test measures well above 1,000,000 page views per hour.
There is also an existing implementation of Sitefinity in a large intranet network with about 7000 computers. In a busy hour, about 3700 users are working on a Sitefinity web site simultaneously.
We suggest that you download our free Community Version, and test it on your web server with the default web site. This will give you a general idea of the performance. For better results we would recommend activating the page caching.
Please, let us know if you need more assistance.
the Telerik team