Most of the newer browsers will print these pages as black on white by default, but some (particularly older ones) may have some trouble. The details of the fix will depend on the browser you are using. Under Windows, Netscape lets you turn off the printing of backgrounds and force text color to black in the Page Setup command under the File menu. Internet Explorer has a checkbox under the menus View->Internet Options ->Advanced which controls the printing of background colors and images. Similar commands generally exist on the Macintosh versions.

If you can't find any other solution (which may happen with older browsers), look for commands which let you override the page's colors (in Netscape 3 you can find this under Options->General Preferences->Colors). However, this will change the appearance of the page on the screen as well as when it prints.