Linux Ubuntu 8.04 Configuration Apache2/MySql/PHP

Hello, I have a cluster of server slices behind a load balancer at RacKSpace Cloud that need to be configured to serve a XML over HTTP post in VERY HIGH VOLUME. I currently am responding at 200 hits/second where inbound data is parsed, run through a php script connecting to a mySql DB, then inserting into a table. I then have a second script that needs to run in the background (screen currently) that will create the XML for HTTP post response. I need someone to configure the [login to view URL] and apache2 settings to maximize response time. I would like to acheive 1,000 hits+response per second. Is this possible? RAM and CPU is not an issue. I need this done yesterday or course, but needs to be a fast project so it can be tested by Tuesday. Thanks and good luck bidding.