well I guess i used it in the wrong context.
if its gonna be a fairly large project and cpu intensive then i suggest going with asp.net,

but if its a large project, but a simple static, and not much queries to execute, php is better.

this is because php is interpreted, while the .net code is compiled into machine language. and at the end of the day, your still using a program to run, where as machine code runs as is. (thereofre making it faster)

its up to you though. generally it will cost you more to run a asp.net website then a php one.