An unlocked taskbar can be moved to any screen edge by "grabbing" it with the left mouse button on an empty area, holding down the left mouse button and dragging it to the left a bit and then back to the bottom (or top, or other side...).
If you drag it to the bottom and the height it too much, position the mouse on the top edge until it turns into a double arrow, hold the left mouse button down, and pull the taskbar down to the desired height.
When you have it where you want, right click an open area of the taskbar and click the Lock the Taskbar option (a check box will appear).
Now, it should stick until you unlock it and move it.
Edited by joseibarra, 04 June 2009 - 05:04 PM.