Make Images Consistent Size

I’ve been using Word Press 2.0 for about three weeks now and have been very pleased with it. There’s one component, however, that I don’t like at all. The image upload function, which I’ve read many other users complaining about, is a bummer.

Word Press 2.0 doesn’t allow me to upload images in their original sizes (it places the uploaded image as a thumbnail in the post and requires that I manually resize it, but when manually resizing it’s hard to approximate the specific dimensions of the original image). My site (www.filmpantheon.com) is a film blog and I want to place two pictures from the film’s I review at the top of every review post. I edit the images I upload in Irfanview before I upload them and they have specific dimensions that I want to keep consistent with every post. My question is this:

Since there doesn’t seem to be a plugin that overrides Word Press’ image upload function (except for various gallery plugins that I don’t want to use), could somebody who’s familiar with PHP write some code for me to insert into every post that will act as a border for the images I upload, so that I can place the images I upload inside this border? (The border will ensure that I don’t manually resize the image too small or too large.)

p.s. the border doesn’t have to be invisible.