.com, .net, .org or .info extension doesn't make any difference to the site in terms of SEO but to get more type-in traffic it's always better to have a .com
The TLD doesn't matter at all for SEO. However, users remember .com a lot easier than the others. So if people just remember your name and not the extension, you'll be sending traffic to the .com version.
EU and JD have hit the nail on the head here. The issue is type-in traffic, where people write your name into the address bar and add .com. They might try again with .net, but maybe not. On the flip side, you have some situations where another TLD is preferable for branding. For example, if your company is called "Networking USA" a .net or .us might be better. A lot of people include the TLD as part of their branding to avoid losing type-in traffic to competitors. So, for example, you can include .net in your logo, so that visual people remember it more easily.
Well..I think it doesn't make any difference in SEO point of view. I am also ranked then as in order .com, .net & .org
.com .net .org .info are the same for MrG and the other serch engine! I like .com, I think that a domain .com is more simple to remind!
I love all the above answers, and I guess it's interdependant on if you are looking for return clients or just to have one time shoppers, usually if I can't find a site I hit up G, and it finds it for me, so extension really isn't that big of a deal if people remeber the main part.