I plan on using nginx to host much of my static content with some minimal php. I'm going to have 2 servers for nginx, but that may be too much hardware for what I need. I'm thinking about dividing them into a total of 4 nginx virtual machines (2 per box). This would allow me to more flexibly divide the resources between nginx and the other parts of the site (which are apache).
Most of the cpu/ram would be used to host the static files and execute system calls from php.
We would use vmware esx to make the virtual machines.
Would we take a major performance hit by running nginx on the VMs as opposed to running it natively on the hardware?