Domain names have very little impact on ranking. In fact they only mean anything, if your domain name and main keywords are exactly the same. I suggest you do not worry about your domain name much. The real thing that will matter is the quality of content and backlinks that your site will have.
For the most part I agree with angilina. The only part I disagree on is that any relevant keywords in your domain domain can help...it does not have to be an exact match to your target keyword. Dashes in your domain name should be no problem, but I wouldn't exceed 2 dashes. Too many dashes does look spammy.
It is recommended to use only 1 dash in the domain. The value of this is only 5 out of 100 if you need a scale of importance. If you use more than 2 dashes, it seems to hurt you.
its extremely hard to get a domain with your targeted keywords these days do using dash can be an alternative in some cases. as long as you have your main keyword in the domain, it doesn;t matter if you have it under all one word or have dashes between each word. its not good for branding but if you are not much worried about branding and your main traffic comes from PPC campaign or organic search, then dash doesn't matter. btw, having your KW on the domain helps a LOT