built-in monitor - but it will delend on how you connect it (VGA or DVI or s-video), so the monitor you connect to will be a factor in the resolution provided.
Under "Graphics and video support":
Extended desktop and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 1920 by 1200 pixels on an external display, both at millions of colors.
Since the video RAM is shared with main memory, you should seriously consider increasing your RAM... You may consider graphics editing as "not graphics intensive" because is is not full motion high-definition video, but some of the photo-editing filters and other processing are indeed "graphics intensive"... Get as much RAM as you can... This suggestion is not limited to the Macintosh environment.
i am looking into a 1.83ghz macbook i no it has an integrated Intel 950 gma i was wondering what resolutions the macbook could use on an external display im mainly going to use the external display for basics things and photo editing but not much graphic intensive things oh the mac has 512 mb of ram