.com vs. .org

I have a little question. I'm about to start on another site and I was wondering how a .com and a .org differ from each other in terms of ranking on search engines and for a sales site. I'm wondering this because I can register a domain with the exact competitive keyphrase of the niche I will be selling with a .org. Does having the exact keyphrase in a domain name help a lot with SERPS? And would a .org be the better way to go in this situation than a .com which wouldn't have the exact competitive keyphrase? Thanks.

Which one would be easier for visitors to remember? If you get the .org and someone accidentally types in the .com equivilent, will they go to a competitior's site? From a pure SEO standpoint I'd prefer the domain with the exact keyphrase only if the words are separated by hyphens, but these other factors are just as important to me.

Why not register both and point them to the same site?

there is not much difference between .com & .org, and if your site is an organization or community site you may want to use the .org

whenever possible I try to use a .com, but you can be very successful with other TLDs

keywords in the domain name are money awaiting deposit

It should not matter. I have a .com and a .net and have not noticed any real differences in SEO. Some people have trouble remember the.net though....people are so used to typing in ".com"

And this is basically the only reason to take a .com over the others.
Like links should point to the www version of the url. People are used to that too.