Images -> Scale Image should give you options for manipulating both the 
size and resolution of the image.

Lee Einer


Lynn David Newton wrote:

>Any GIMP experts out there? This may seem like a dumb
>question, but so help me, I've tried this at least ten
>different occasions and I can't figure out how to do
>it.
>
>I have a high-resolution JPEG picture: 1600x1200
>pixels. All I want to do is reduce it: save it as a
>1024x768 or maybe 640x480. I know about Tools ->
>Transform Tools -> Crop & Resize. That works great for
>cropping, but how do I simply shrink the whole image?
>
>I used to use the shareware program xv for this. You
>can select size and say 50% or whatever, and it will
>resize the image retaining the aspect ratio.
>
>There's gotta be something simple that I'm missing.
>