You could scale up on the SQL Server box - more
processors, more ram, faster disks (raid 10 for data),
filegroups etc. Assuming all this is done, have a look at
(a) federated database servers (aka Distributed
Partitioned Views).
(b) using log shipping/transactional replication to
maintain a reporting server to offload reporting
requirements.
HTH,
Paul Ibison
(recommended sql server 2000 replication book:
http://www.nwsu.com/0974973602p.html)