No matter what the nature of your business, a web presence is almost essential these days. Whether your site is simply an online brochure, or you're doing all your sales through the web, your reputation is on the line. Poor design, unreliable web hosts, bad network connectivity - these things can all impact your business's appearance. But it doesn't happen by accident, and you need to work with competent people to make it happen. You need absolute reliability above all else.
Web surfers are an impatient lot.
If you're getting any kind of traffic to your site, any downtime equals lost business or exposure. Nothing will frustrate web surfers more than not being able to reach a site. I've found that people tend to remember frequent downtime, and it can reflect poorly on your organization. Also, these days, many businesses are relying on paid advertising to direct qualified traffic to their site. Every moment your provider is down is advertising money down the drain.