Not sure exactly what you're experiencing here, but I can make one suggestion regarding the rendering of images in emails.
If you are using the 'padding' attribute to create spacing around your image, for example, I have known this tag to not play well with the Office client. If you are using padding, try replacing that tag with 'margin', or, better yet, resize the raw image file to the exact size you need it via photoshop so you can avoid inline styling altogether.
If this isn't what you're experiencing can you provide a little more detail? I have never seen a resizing issue with landing pages per se - just discrepancies with vertical spacing during cross-browser testing for the most part, so I am not sure I can speak to that aspect.