It's worth noting that in Xen Media Gallery, the EXIF data is retrieved from the image and saved before any manipulation happens.
So, you should find that if your users are uploading their images using XMG, the EXIF data will remain even after a resize (a side effect of this is the actual dimensions reported in the EXIF section are of the original image, not the resized image). The XMG GALLERY BB Code also is usable directly from within the Quick Reply editor in threads. If you use the "Extended" GALLERY BB Code then images displayed in posts have an Information tab which makes the EXIF data viewable right from within the post.