I would like some suggestions for hardware for the following:

SQL Server 2008 which will be used for a supply chain automation application.
Transactions will be performed via RF bar code scanners for warehouse
operations, inventory control and production. All transactions will
first be stored in SQL Server, which will have an interface to the ERP
system which is on UNIX. Transactions will be real-time and not batched.

Current estimates when all phases are complete are for over 300,000
transactions per year, or over 10,000 per business day. Transactions do not
have to be stored long term on this server, as the ERP system remains the
system of record.

What are your thoughts regarding hardware? What is the most important thing
to spend our money on?

Would this require a dedicated server or would it be OK to put this on an
existing data warehouse box that is lightly used?