How to Arrange Multiple Windows Side by Side in Windows Vista
When you want to work with two files or programs, it’s usually much more convenient to be able to see both files at the same time. You can arrange multiple windows side by side on your desktop in Windows Vista very quickly and easily. You can tile them side by side (vertically) or from top to bottom (horizontally).
Make sure both the windows are open.
Both icons need to appear on the Windows taskbar.
On the taskbar, click one window’s icon; then hold down the Ctrl key and click the other window’s icon.
Right-click one of the selected icons and choose Show Windows Stacked or Show Windows Side by Side.
The selected windows are tiled.