I found this in a few different places around the 'net - hopefully it's helpful:

Opening a Web Page in a New Window

When surfing the Web, sometimes you might want to check out a Web page and at the same time stay on the page that gave you the link in the first place.

With Internet Explorer 6 in Windows XP, that's exactly what you can do:

• Simply press and hold down the SHIFT key while you click the link. The page will open in a new Internet Explorer window.

Need to look at two Web pages side by side? That?s easy too. To view any open windows side by side:

• Right-click an empty part of the taskbar (the bar at the bottom of your screen), and click either Tile Windows Horizontally or Tile Windows Vertically.