Using page id's, finding page id's?

Hello all,

In my installation of wordpress I’m using the “post name” permalinks system.

In a file I’m trying to modify I’m using if(is_page(array(x,y)) ) with x and y being the page id’s. Can I use the pages permalink name as a page id? If not do I have to use page id numbers, if so how would I find them now with permalinks set on “post name?”
Thanks for any help.

PChuprina