What does a used 5DMkii vs new 7d do here? Am I crazy? Can I do sports with the 5D?
IMO you should stop this thought right now in his tracks, 'cause I doubt that you will be very happy with a 5D Mk II. While it's certainly possible to shoot nearly anything with any camera, the 5D2 certainly wouldn't be what I would choose to shoot sport, maybe with the exception of chess and Tai chi.
I'm not saying that the 5D2 is a bad camera, but it wasn't designed for such use. Downsides are: low FPS and a AF which is far from ideal for fast moving objects and you would be more or less stuck with the center AF-point. Of course, if you know the sport very well and are able to anticipate the moment to release the shutter you can take excellent pictures, but the amount of keepers will be significantly lower than with a 7D. The full frame is another 'downside' if it comes to sports, 'cause you don't have the crop-factor and will need longer and more expensive lenses. 70-200 on a 1.6 APS-C results in framing equivalent to 112-320mm while on FF it's just 70-200. With a 7D you will also warmly welcome the AF with its 19 AF fields and sophisticated options.
It think you are pretty much set with the 7D and the 70-200 for the sports stuff. So that leaves you with the question what else you're going to do with the camera.
Lot's of advice here based on people's own preferences but I'm not clear yet what your other use may look like. Do you have a need for wide angle (such as architecture, landscape, etc)? Do you have any use for fast lenses (and to me that means control over depth of field and not so much being able to make pictures in the dark...)? Will you try to shoot portraits and if so what is your preferred focal length for that? Again, how important is good "bokeh" for you? Is weight and size a concern? Do you want to get into flash photography or not at all?
So in other words I'd be very careful with some of the blanket statements here about what constitutes "general purpose" use. Everyone has a very different view of that I suppose. And some of this is always a compromise - especially with the limitations of a cropped sensor if you answered "yes" to any of the questions above...
I personally would always go with the fastest lens I could afford in the desired focal range. But that's me and may be completely irrelevant for your preferences.
Thank you for the insight.
Being outdoors and shooting the sports is priority #1. However, I do know that once I get into the gear I will want to explore other options. Landscape, portraits, etc. When not shooting sports, I do know that I want to take photos that pop and have that "gooey" feeling when not in focus.
Please be gentle, I'm coming over from a very old Nikon D70 with bad glass.
on what 7enderbender
For other stuff than sports the 5D2 has its upsides (better image quality at low ISO, 'sexier' depth of field), but since sport is your #1 priority and money is of relevance, I would - again - suggest that you go with the 7D. Otherwise I probably would suggest a 1D4 or a 5D3.
With the 7D you will have no problem "exploring other options" and can decide in a year or two if you want to change the body. Well, this brings us - again - to the topic of the sustainability of lenses...
Changing lanes is easier (and cheaper) if you don't have to consider the cost of new glass.
If you want to play with portraits, the 50/1.8 wouldn't be a bad choice, 'cause it's a rather cheap but not bad lens from what I hear (sorry, no personal experience with it.)
On the other hand if you want to try landscapes you probably should think about investing into a wide angle lens like to 10-22 or the Sigma 10-20.
farmdwg - one thing that I found that helps me decide is to go to 500px.com and type in the camera and lens in the search bar. It gives me an idea of what the kit can do. [...] you can see the IQ in those situations.
Personally I would be very careful! Postprocessing can do A LOT to a image and this is much more valid when we are talking about 'online'-resolutions. It's a quick job to bring a bad image, be it because of the photogs skills, the lens and/or the camera, to a point where it looks fabulous, as long as viewed only on a screen at low resolution. Online galleries are swampy terrain when it comes to judge a photog or some gear.