I use photobucket to upload my pictures to forums, and they have a facility to alter the size of your pictures.
Also what imaging software are you using? Does it enable you to alter the image size? If so, then save it to 1024 pixels on the horizontal, the vertical should then automatically set itself. I use Adobe Photoshop 5, I bought it on EBAY for a fiver.
If its old Boeings your after, this beast is over 30 years old.
