Some of those sized pics looked way too stretched out of proportion. While others look great.
My best advice is to ensure first that the width of your photo is 500. You can crop it to obtain the 500 pixel width. Save it. Then re-open the photo and use the crop tool to get a 45 pixel height. I took Tones' photo and first re-sized it to get a 500 pixel width. Then I used my cropping tool to grab a portion of the photo and crop it to a height of 45 pixels. Took 3 tries before I got the 45 pixel height. Here are two separate results.
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I like @VRYALT3R3D's advice with Paint, but I use Adobe Elements. So I had to do it a bit different.