But it is always a plus if the domain name in included.
You might want to check out
Adult SEO Blog - there is a tutorial on building a search engine friendly website, that begins with the
picking of a domain name.
The SEO tutorial is in
blog form so you will start at the end, and work your way up.
My theory on building a SE friendly site is the same as building a house. You put the wire in the walls before you put up the drywall, so you should build your site with the SE's in mind.