I don't have the original files any more so I can't magic up a simulated 7D image, and even if I could, it would look sh!te because it would have to be an upscaled image. However, the maths is quite simple. The long dimension of a 7D image is 5184 pixels vs 4752 of the 50D. The linear increase in size, when viewed at 100%, is 5184/4752 = 1.09. That's the equivalent of fitting a 1.09X teleconverter, but with no loss of light due to aperture reduction.
To put that another way - on my screen the 50D starling shot is about 90mm tall. The equivalent 100% crop from a 7D would be ~98mm tall.
Personally I could not care less for 18MP vs 15MP. It's too small a difference to be bothered one way or the other. What I am far more interested in is the noise performance. When you want to crop hard, which is often why birders buy these high resolution, cropped sensor cameras, it's no flipping use if noise kills the detail. The camera specs look great, but I shall be studying the reviews very carefully, regarding noise and AF performance particularly, before parting with my cash.
My 50D will handle the high resolution demands, at low ISO. My 1D3 will handle demanding AF situations and high ISO shooting. I'm not sure yet what the 7D will bring for me that I do not already have covered. The integrated wireless flash commander is a big bonus but I think video will be no more than a curiosity that will soon lose my interest. There are lots of other nice features, but nothing that will really sway a decision. For me it mostly comes dow to AF performance and IQ. The rest is just gravy. For those who have neither a 50D or a 1D3 I think the 7D is going to prove a very interesting camera indeed. Perhaps if I was starting from scratch, or only had an 40D or a lesser camera then the 7D would be a very strong contender as my next camera.