How important is the main keyord in the domain name, if you want to make one site about music and you get two domains, music.com and anothersite.com, and both will have good seo, the first domain will rank higher on google just for that keyword in the domain name ?
It is important, but not as important as it once was. SE's look at many more factors than just the name, but if your domain is music.com, the site most likely won't be about deep sea mammals. The other way the domani name makes a difference is when people link to you with only your url. for example, if someone links to you with http://www.music.com, SE's will break that down (because periods are word seperators just like spaces), and you'll still get your music keyword in the anchor text. If your url is anothersite.com, anybody linking to you with only your domain name will not be using any of your keywords in the anchor text.
100% true ! I can add that search engines are now more and more obliged to consider domains without generic keywords if they want to discover new websites since all the generic domains were registered long time ago.