You ALWAYS want at least one of your primary keywords in your domain. It adds to the credibility of the site, makes it easier for people to recognize what should be on it, helps with ranking, and also gives you more FREE advertising perks when running your PPC campaigns - Google highlights search keywords in the domain or display url.

It's important, but it's not that important.

The title and tags of your page are far
more important then a domain name.

Also, the first 2 lines of your content are
crucial. I'd not worry about keywords
in the domain name too much, instead
invest more optimization in content and title.

Igor

Having 5 webpages on the same site with keywords in titles is much better, these pages will have a "synergistic" effect on each other ranking..

I completely disagree with every reply so far. All other things being equal, you will much more easily rank for each of those 5 keywords if you set up a domain/site around each vs. picking one of them for a domain/homepage and then having the other 4 as inner pages. Google values an exact match in the domain name for a search term over having that term appear just anywhere in the URL. Again, all other SEO issues being equal. It's not even close, in my experience.

John

Have to agree with John on this one .

I don't know how important Google's take is on exact domain name matches ... but I do know that it is hard to get better rankings with relative domain/ exact subpage match, even with a few more links than the exact match .

Now I said it is hard ... not impossible .

One of my long tails is almost impossible to capture from a very unrelated domain for the fact they have several incoming from an obscure little site called yahoo.