Setting your browser to print lines:

Internet Explorer
IE typically is not set to print background color or images, including table cell colors. To get the table cells colored backgrounds to print, click on the browser’s Tools menu. Select Internet Options, then click on the Advanced tab. Scroll down to find the Printing heading and check the box called Print Background Colors and Images. This setting affects both page backgrounds and table cell backgrounds.

Netscape Navigator
Netscape seems to always print colored table cells either with colors or shading, depending on your printer. But you can separately control whether it will print the page background color or image. Click on the File menu, then select Page Setup, and then in the Page Options section, check Print Backgrounds to include the page background in your printout.

Mozilla
In Mozilla 1.6 for FreeBSD (and possibly on other platforms), Select File -> Page Setup... and other Options, check the box marked "Print Background (colors & images).Earlier versions of Mozilla do not appear to have a way to print the background color of tables.

Apple Safari - OSX 10.2/10.3
By default, Safari will print the colors in the backgrounds of tables. There does not appear to be a control available to disable this behavior.