If you're struggling to decide whether investing in your website or advertising is more important, I'll save you the trouble: the correct answer is that you need both.
If the website is like the heart - in that you need it to survive - your marketing campaign is like the brain.
Much like our neural system controls the way our vital organs operate, an effective advertising strategy makes everything else work the way it's supposed to. It's what gets customers interested in your product, enticing them to locate your website and, ideally, to make a purchase.
But like the brain, your marketing campaign can never, ever stop working - not even for a brief time period.