Am in the process of proposing a .NET architecture for a client who wants to rewrite his website from ASP to .NET

Proposed architecture:
ASPX Code behind --> Web services --> Business Component --> Database Component --> Stored procedures --> Database

Web Services will be used to communicate between the presentation layer and application server.
The technology is ASP.NET, VB.NET on COM+ and Oracle on Unix box.

Expected concurrent users is about 3000! For this kind of hit rate, what should be load balancing support, hardware and software support, server configurations?

What are the technical risks in implementing this architecture that can be identified and raised now?

Any pointers and inputs would be very useful.
Thanks,
Jemima.