Hello,
I am running MySQL 4.0.15 for a mortgage lead website. The database is getting to large and is being bogged down by 7000 members logged in at once running queries.
What options are available?
I thought about running a slave database to hande the overflow.
Can someone point me in the right direction.

Have you looked into replication or clustering? For replication I know that you can basically load balance SELECT queries between the slave servers. UPDATE, INSERT, etc. statements have to be issued to the master so it can propagate the changes to the slaves. So if your database is SELECT heavy replication might help.

That is what I thought, can this be done on the same machine or do you need a separate server?

It can be done on the same server, but my feeling is you will still have the same effect as now if you place the replicate on the same box/os. If your current bottlenecks are network and/or disk access you will probably encounter the same issue by placing the replicate on the same hardware.