If the one server will be running all components in the stack (HTTP service and database service, and whatever else) then the answer is absolutely yes.
If the machine will only run the front-end services, the answer is still most likely yes. At the basic level, web serving capacity is driven primarily by memory capacity. After that, things like I/O and process forking come into play. I think you're probably better off with more cores, because the httpd won't care too much about clocks. The newer quad-core CPUs, by and large, have faster memory interconnects also, which will surely help.