You can also change the colors of your text so that it's more readable against your background, however. That's the hard part. There are some utilities to help you. Check out Elizabeth Hamilton's Color Machine. Light colored backgrounds make text easier to read.
Dark colors are eye-catching, but also tiring to the eye.
If your page will have mainly graphics, a dark or patterned background can act as a good contrast for those graphics. Pictures seen against a black or dark blue background often look more exciting than pictures against a white background. If your page is a mixture of text and graphics, it may be more legible on a solid background. Text-intensive pages usually work best on a solid background. You seldom see books with pages that have a patterned background - because they would be difficult to read.