PHP app & Server Load

Hi, This is slightly OT... We're wrapping up a new PHP/MySQL driven web site built on the Zend Framework. We're anticipating a couple hundred thousand members with several thousand of them coming to the site at once. I'm trying to figure out how to determine how many servers we need to support the load. I've done initial testing on a Xeon 3220 server, but we're looking at an i7 cpu based server now. Anyone know a good way to estimate load based on actually numbers compared to benchmark results from intel on a faster server? -- -Dan Joseph www.canishosting.com - Unlimited Hosting Plans start @ $3.95/month. Promo Code "NEWTHINGS" for 10% off initial order http://www.facebook.com/canishosting http://www.facebook.com/originalpoetry