A visitor will not accept a badly designed business website. (You wouldn't either.) You know this instinctively.
Alright. You need to get good design. But how?
Some of the answer we get from fashion.
Right now a change in fashion can be seen at sites built for Web 2.0. The bold lines, bright colors, use of gradient fills and large type faces are popular and becoming wide spread. Another, earlier, fashion change is apparent on corporate web sites. Ten years ago they had gray backgrounds and often emphasised burgundy as the main color: today you will never see this combination on a big business website. So, like design is contantly moving and shifting off the 'Net, it is frequently changing on-line.
This is what fashion does. Keep your site somewhat in line with fashion so it stays fresh and lively for your visitor. For this reason check your site every two or three years with a view to redesigning it.
Design has a technology angle.
Satelite pictures and street from Google Earth, are now regularly turning up on websites. Because a map will be useful for certain types of customer, many sites are designed to include this cutting-edge technology. Email is another example. Early web sites didn't have the form-to-email box we now recognize on our contact pages. In fact, they didn't even have contact pages. Then, a visitor clicked on the words of email addresses and emailed with the email page that popped up.
Use the latest technology on your site if it will help your visitor, and your site will work better for them.
Website design is pushed by what visitors think looks cool and what you know is technically possible. To keep both you and your visitor happy, take them both into account when you build your web site.